Moderate president-elect Hassan Rowhani said Saturday his victory opened a new path for Iran to engage constructively with the international community and ease tensions raised by Tehran's nuclear ambitions.

"Moderation in foreign policy means neither surrender nor confrontation but constructive and efficacious interaction with the world," Rowhani said in his first live televised speech since being elected on June 14 to succeed Mahmoud Ahmadinejad.

Iran is at odds with world powers over its controversial nuclear ambitions, which the West and Israel suspect have military objectives, and its support for the embattled regime of Syrian President Bashar al-Assad.

Rowhani, who thrashed his conservative opponents by winning almost 51 percent of votes, did not mention either issue directly.

But he did say he would move to ease tensions after he formally takes office on August 3.

Under his administration, "interaction and dialogue will be based on reciprocity, respect and mutual interest, and seeking mutual detente," Rowhani said.

His tone contrasted with Ahmadinejad's eight years as president, which were marked by fiery, contentious remarks on a wide range of international issues, including Iran's nuclear drive, arch-foe Israel's right to exist and the Holocaust.

Ahmadinejad, whose disputed 2009 re-election plunged Iran into domestic turmoil, has also drawn the ire of domestic foes for his populist economic agenda, and what his critics call mismanagement of vast oil wealth.

Rowhani pledged to replace that approach with "moderation" in which "a balance must be achieved between realism and idealism".

"People have chosen a new path... one that is of change," he said of the ballots cast by nearly 37 million voters, a turnout of more than 72 percent.

He also repeated his campaign promise of employing "the most qualified people with any mindset on the condition of moderation" to form a trans-factional cabinet "that is not in debt to any faction or (political) group".

Rowhani also vowed to fight for "all of Iran's rights and the nation's demands", but without elaborating.

Iran insists its nuclear activities are aimed at civilian applications, under which it has the right to enrich uranium, whose highly enriched form can be used as the fissile core of an atomic bomb.

Rowhani campaigned on promises resolving the nuclear stand-off with the West and lifting sanctions, which have cost the economy billions in vital oil revenues and foreign investment, leaving Iran struggling with raging inflation, high unemployment and a depreciated currency.

A 64-year-old mid-ranking cleric, Rowhani headed a relatively moderate nuclear negotiating team under reformist president Mohammad Khatami in the early 2000s, when Tehran agreed to suspend its enrichment activity.

But that programme, whose final decisions rest with supreme leader Ayatollah Ali Khamenei, resumed in 2005 when Ahmadinejad was first elected.

Iran has since then massively expanded its facilities for the enrichment of uranium, an operation under the supervision of the UN nuclear watchdog.

Rowhani is considered a regime insider as he has held senior political posts since the inception of the Islamic republic, including representing Khamenei in the top national security council since 1989.

He also enjoys the widespread support of reformists and moderates, in particular that of pragmatic two-time ex-president Akbar Hashemi Rafsanjani.

Rowhani's election has created a surge of hope among the population that there will be change, including the easing of restrictions at home.

In his address on Saturday, he urged the authorities to be more tolerant over civil freedoms.

"Joy and exhilaration is the people's right," he said of two nights of street parties, one after the announcement of his election and another after Iran's June 18 qualification for the 2014 football World Cup in Brazil.

Rowhani thanked the police for allowing the festivities that ran past midnight, but warned: "Don't impose too many restrictions. Our people are moralistic and aware of the Islamic, political and ethical boundaries."

He also called on the state broadcaster to avoid "double standards" when reporting on world affairs.

Without giving any specific examples, Rowhani said that wrongdoing anywhere in the world should be criticised as an "injustice," even if "it happens in a friendly country".

Iran has strongly backed the Assad regime in its fight against armed rebels, whom Tehran regards as "terrorists" backed by Western and Arab countries -- a term regularly repeated on the Iranian state broadcaster outlets.