Any US military action against Syria would amount to “support for al-Qaeda and its affiliates,” Damascus has said.
Syrian Deputy Foreign Minister Faisal Mekdad also told the BBC that armed groups backed by America – not Syrian troops – had used chemical weapons.
The US says it has evidence that Damascus used the nerve agent sarin in a deadly attack in August.
President Barack Obama has vowed punitive action but wants Congress to vote on the issue first.
The alleged chemical attack took place on 21 August in the eastern suburbs of Damascus. The US says more than 1,400 people were killed, including 426 children.
The French government has said it will hand over its own evidence to French lawmakers on Monday, linking the Syrian regime to the attack.