Ayrault made the remarks during an emergency conference at parliament where members had gathered to debate on France's response to the Syrian crisis, Xinhua reported.
"Not to act is to close the door to a political settlement of the Syrian conflict. Yes, the solution to end the Syrian crisis is political and not military," Ayrault said.
He stressed that "the serious threat associated with the use of chemical weapons compels us to act".
The parliament emergency session came after a majority of French people expressed their support of putting a military intervention in Syria to a parliamentary vote. But the prime minister ruled out the vote and said Wednesday's meeting was only planned for a debate.
"In any case, the final decision will be taken by the president when the coalition will be formed, the only way to create the conditions for action," Ayrault said, adding that Paris will neither act alone nor send ground troops in the conflict-torn country.
According to media reports, a French intelligence report presented to lawmakers Monday showed forces loyal to Syrian President Bashar al-Assad were behind the alleged chemical attack in Damascus Aug 21.
But the Syrian president denied the allegations and said in an interview with French daily Le Figaro Monday that France will face negative repercussions if Paris and its allies launch a military intervention against his country.