Alain Juppe also demanded that 300 UN observers for Syria should be deployed within 15 days and said France has all but set a May 5 deadline for the regime to comply with special envoy Kofi Annan's peace plan.
"We think this mediation should be given a chance, on the condition that the deployment of the observer mission happens quickly," Juppe said after a meeting with Syrian dissidents at his ministry.
The plan isn't dead, he said, but "it is severely compromised"
Annan's scheduled May 5 report on the state of a cease-fire called for under his plan will be "a moment of truth: Either this mediation is working, or it isn't," Juppe said.
"We cannot allow ourselves to be defied by the current regime," he added, insisting that Assad's regime had not held to the six-point plan under Annan.
The Assad regime's crackdown on a popular uprising is estimated to have killed more than 9,000 people over the past 13 months.
Juppe's comments signaled that Paris is increasingly lining up behind a U.S. position laid out by Secretary of State Hillary Rodham Clinton in Paris talks last week by key members of the so-called "Friends of Syria" group.
He said France has been discussing with other world powers the prospect of invoking Chapter 7 of the UN charter, which allows for action that could be militarily enforceable.