"Today, we can say that Raqa is surrounded and the battle will begin in the coming days," he told France's CNEWS television.
Raqa is one of two major strongholds of the IS along with the Iraqi city of Mosul, which Iraqi forces in October launched a massive operation to recapture.
"This will be a very hard battle but essential," Le Drian said.
IS is under pressure from several directions in northern Syria, with Russia supporting its Syrian ally President Bashar al-Assad on one front and Turkey providing air cover for rebel groups battling the jihadists on another.