Syria on Sunday said US President Barack Obama has grown "hesitant... and confused", after he postponed a threatened military strike on Damascus pending a vote in Congress.

"President Obama was clearly hesitant, disappointed and confused when he spoke yesterday," Deputy Foreign Minister Faisal Muqdad told reporters, in the Syrian regime's first reaction to Obama's announcement.

Muqdad also slammed France's government as "irresponsible" and accused it of trying to dupe its own people over its support of a military strike on Damascus over an alleged gas attack.

"There is a responsible government in Syria but there is no responsible government in Paris," he said. French political leaders had "falsified facts and supported organisations like Al-Qaeda."

"We believe the (French) president and his foreign minister are deceiving the French people to justify the failed policies against Syria, and they will not succeed," he told reporters in Damascus.

After Obama delayed any attack on the Syrian regime until after Congress meets on September 9 following summer recess, Muqdad urged US lawmakers to show "wisdom" in their vote on military action.

"We ask the US Congress to show wisdom," he said, once again denying his regime was behind an alleged poison gas attack on August 21 that precipitated American and French calls for military action.

"Chemical weapons have been used by Al-Qaeda and those who are in their pay thanks to what Turkey, Saudi Arabia and other countries supply to these terrorists," he said, using the government's term for anti-regime rebels.