The White House Tuesday dismissed an aggressive claim of victory by Iran's President Hassan Rouhani over an interim nuclear deal, and attempted to face down rising domestic political pressure over the pact.

Washington said Rouhani's comment that world powers were now bowing to Tehran was a symptom of domestic politics and insisted the deal, curbing aspects of Iran's nuclear program in return for limited sanctions relief, hinged on its words and not its rhetoric.

"It is not surprising to us and nor should it be surprising to you that the Iranians are describing the agreement in a certain way towards their domestic audience," spokesman Jay Carney told reporters.

"It does not matter what they say, it matters what they do."

Rouhani's comment, on his official Twitter account, played into complaints of hawkish members of the US Congress that the deal, due to come into force on January 20, gave too much up to Iran for too little in return.

"Our relationship w/ the world is based on Iranian nation's interests. In #Geneva agreement world powers surrendered to Iranian nation's will," the tweet said.

The White House is fighting a battle to prevent Congress from slapping a new round of sanctions on Iran which it says could cause the Islamic republic to walk away from the negotiating table, and eventually push Washington into a war to thwart Tehran's nuclear program.

Supporters of tightened sanctions say they have at least 59 votes in the 100-seat Senate and may be heading towards the 67-vote threshold needed to override the veto that President Barack Obama has promised. There is also strong backing for new sanctions in the House of Representatives.

Some lawmakers have been irked by White House warnings that voting for new sanctions could unleash a train of events that could lead to war with Iran.

Senate Majority leader Harry Reid has so far declined to bring the sanctions bill to the floor, noting that 10 key Democratic committee chairs have called on him to thwart the passage of any measures that could scupper the nuclear diplomacy.

Reid spoke a day after Obama publicly called on lawmakers to hold off on new sanctions to avoid disrupting his nuclear diplomacy -- taking place after more than three decades of Cold War-style antagonism between the Islamic republic and a nation it derides as the "Great Satan."

Lawmakers who support the bill say tough sanctions brought Iran to the negotiating table and stiffer measures would increase Obama's leverage in talks between Tehran and the P5+1 group of world powers.

The new measures target the petroleum, mining and engineering sectors of Iran's economy, but supporters say they would only come into force if Tehran stops negotiating in "good faith."

Some lawmakers have not taken kindly to warnings from the White House that backing more sanctions was was effectively a vote for war.

"I think that is absolutely untrue, an irresponsible assertion, and ought to be clarified and retracted by those who have made it within the administration," said veteran Democratic congressman Steny Hoyer, who nevertheless welcomed the interim deal as a positive step.

The Obama administration is also denying claims that the interim deal reached after weeks of talks in Geneva, included a secret side deal on implementation.

"Let me be very clear: There is no secret agreement here," said State Department spokeswoman Marie Harf, adding that the terms of the agreement would be released to Congress once Washington had consulted with its partners in the talks.

While the United States and Iran have held direct talks for the first time in decades during a diplomatic thaw triggered by Rouhani's election last year, the foes are still estranged on a string of other geopolitical issues.

Washington on Tuesday registered a sharp protest at a visit by Iranian Foreign Minister Mohammad Javad Zarif, a key player in the nuclear talks, to the grave of Imad Mugniyah, a former leader of the Hezbollah militia in Lebanon.

National Security Council spokeswoman Caitlin Hayden said that Mugniyah was responsible for the deaths of hundreds of people, including Americans.

"The inhumane violence that Mugniyah perpetrated -- and that Lebanese Hezbollah continues to perpetrate in the region with Iran's financial and material support -- has had profoundly destabilizing and deadly effects for Lebanon and the region," Hayden said.

Obama urges Congress to give Iran diplomacy a chance
Washington (AFP) Jan 13, 2014 - President Barack Obama urged the US Congress to give peace with Iran a chance Monday, as lawmakers lined up behind new sanctions despite warnings they could doom an interim nuclear deal.

Obama said that the six-month pact due to go into force on January 20 after being concluded at the weekend, offered a "door of opportunity" for Iran to have better relations with the outside world, after decades of deep antagonism with the United States.

But he said that if Iran fails to live up to the terms of the deal, which freezes aspects of its nuclear program in return for limited sanctions relief, he would support new punitive measures to stop Tehran getting a nuclear weapon.

"My preference is for peace and diplomacy," Obama told reporters in the Oval Office.

"This is one of the reasons why I've sent a message to Congress that now is not the time for us to impose new sanctions. What we want to do is give diplomacy a chance and give peace a chance."

The White House has previously warned that Obama will veto any bill enacted by Congress to impose new sanctions on Iran, fearing it could prompt Tehran to walk away from the negotiating table or undermine its negotiators among regime conservatives back home.

But there are increasing signs that bipartisan support for the bill on Capitol Hill may be nearing the two-thirds majority required to override such a veto.

It is currently unclear if and when the bill will be brought up for a vote in Congress. The president will have a chance to press home his case for a delay in new sanctions when he makes his annual State of the Union address on January 28.

Lawmakers who support the bill say tough sanctions brought Iran to the negotiating table and stiffer measures would increase Obama's leverage in talks between the Islamic Republic and the P5+1 group of world powers.

Obama has insisted that Washington must test Iranian President Hassan Rouhani's willingness to honor a pledge to seek a peaceful nuclear deal, despite opposition from many hawks on Capitol Hill and deep reservations by America's closest Middle Eastern ally, Israel.

His aides say that if new sanctions force the nuclear talks to collapse, Washington could be forced into another war in the Middle East to thwart the Islamic Republic's nuclear ambitions.

Obama stresses that he has not taken the option of using military force off the table, but he has warned that such action may not be decisive and could unleash waves of unintended consequences across the Middle East.

White House spokesman Jay Carney said new sanctions would have the opposite effect to the one intended by key sponsors, Democratic Senate Foreign Relations Committee Chairman Robert Menendez and Republican Senator Mark Kirk.

"It could, if they were to do it, actually weaken the sanctions structure that's in place by undermining faith among our international partners and providing Iran the opportunity to say that we have been negotiating in bad faith," Carney said last week.

In a Washington Post editorial, Menendez described the initiative as a "diplomatic insurance policy" against Iran. He said his bill would impose immediate extra sanctions on Iran if it became necessary but would not come into force while "good faith" negotiations were under way.

"Should Iran breach this agreement or fail to negotiate in good faith, the penalties it would face are severe," he wrote.

New sanctions would further target Iranian petroleum products and the mining, engineering and construction sectors.

A senior US administration official told AFP that the first $550-million (400-million-euro) installment of $4.2 billion in frozen assets would be released under the interim nuclear deal early next month.

"The installment schedule starts on February 1 and the payments are evenly distributed" across 180 days, the official said.

Analysts say unblocking the funds would breathe new life into the economy and provide much-needed relief across Iran.