"It seems obvious to me that the question of lifting the arms embargo will be increasingly on the table due to the evident imbalance between Bashar al-Assad, who is being supplied with powerful weaponry from Iran and Russia, and the National Coalition, which does not have such weapons," Fabius said after talks with his 26 European Union counterparts.
The EU late last month amended its arms embargo on Syria to allow member nations to supply "non-lethal" equipment as well as training but stopped short of lifting the embargo entirely.
"This question ... will need to be put on the table again very quickly because it is inadmissible to allow such an imbalance to lead to the massacre of an entire population," Fabius said on Monday.
It was meanwhile necessary to use all political and diplomatic channels available, in agreement with the Americans, the Russians and Arab nations, "to try to find a political solution" to the conflict, he added.
Fabius spoke after EU foreign ministers held talks with UN-Arab League envoy to Syria Lakhdar Brahimi on ways of stopping an "appalling" conflict about to go into a third year.
"We need to stop the killing, we need to stop the violence," said EU foreign policy chief Catherine Ashton of a conflict that has sent a million Syrians fleeing the country and left some 70,000 people dead.