Extremists cannot be defeated by countries that have "spread terrorism", Syria's President Bashar al-Assad said Tuesday in an apparent jab at members of the US-led anti-jihadist coalition.

Speaking during a meeting with a senior Iranian official in Damascus, the Syrian leader took aim at countries he said backed "terrorists," a term his regime uses for all those seeking his ouster.

"Fighting terrorism can never be done by those countries that helped create terrorist groups, giving them logistical and financial help and spreading terrorism around the world," state news agency SANA quoted Assad as saying.

He made the remarks during a meeting with Ali Shamkhani, secretary of Iran's Supreme National Security Council, who arrived in Syria earlier Tuesday.

The comments appeared to target the United States and other members of the coalition now carrying out air strikes against the Islamic State (IS) group on Syrian territory and in Iraq.

Damascus has long accused Washington and Arab nations that back the Syrian uprising of "supporting terrorism" because of their support for the opposition to his regime.

SANA said Assad and Shamkhani warned that the United States was approaching the issue of defeating extremists with "covert agendas that do not serve the people of the region."

Syria has had a largely muted reaction to the start of US-led strikes on its territory, despite earlier insisting any such action should be coordinated with its government.

It has said Washington gave it prior warning of the strikes, but insists military action against the IS will not succeed unless the coalition is expanded to include the Syrian government and its key ally Iran.