A senior Iranian official warned in Damascus on Sunday that US interests in the region would be at risk if Washington launched a military strike against his country's ally Syria.

Iranian officials have issued stern warnings against US-led military action targeting Syria and the latest came from the chairman of the foreign policy committee of Iran's parliament.

"I hope that the United States will not undertake any precipitated and irrational action, due to the sensitive situation in the region," Allaeddine Boroujerdi told reporters.

"The Americans cannot threaten the countries of the region and expect that their own interests will not be threatened," he said, a day after talks with Syrian President Bashar al-Assad.

US President Barack Obama accuses Assad's regime of unleashing poisonous gas on Syrian citizens last month, killing hundreds in Damascus suburbs.

But Obama on Saturday said he will seek congressional approval before launching a punitive strike on the Syrian regime.

"If the United States carry out a foolish act, our response will be decisive," said Boroujerdi, in remarks translated from Farsi into Arabic by an interpreter.

On Saturday, the head of Iran's powerful Revolutionary Guards warned that a US strike would trigger "reactions beyond" Syria and bolster extremism.

And Iran's supreme leader Ayatollah Ali Khamenei has said a strike on Syria would be a "disaster" for the region.