Jean-Yves Le Drian said completely closing Syria's airspace was equivalent to "going to war" and would require a willing international coalition that does not yet exist. The minister, however, told television station France 24 that France would participate in such an operation if it followed international legal principles.
For now, though, he suggested that a partial closure - which US Secretary of State Hillary Clinton said Washington was considering - should be studied.
France, like other Western countries, is sending supplies to the rebels fighting Syrian president Bashar Assad, but the international community has been reluctant to intervene in the conflict as it did in Libya.
Le Drian reiterated that any solution must begin with Assad's resignation.
Later in the evening, President Francois Hollande said European countries were working to help unite the country's fractured opposition, to which France and other countries are already sending supplies.
Hollande, who was meeting with German Chancellor Angela Merkel in Berlin, added that France is organizing a UN Security Council meeting at the end of the month to discuss increased humanitarian aid for Syria.