French planes bombed an IS telecommunications centre, described by Le Drian as a "propaganda centre", the minister told the BFMTV television channel, adding that France has hit IS targets seven times since Monday, mainly in Iraq but also in Syria.
"Daesh [a pejorative Arabic acronym for IS) is retreating in Iraq," Le Drian went on, pointing out that it has lost the towns of Sinjar and Ramadi but advising caution in predictions.
Defence ministers from seven countries - France, the US, Australia, Germany, Italy, the UK and the Netherlands - are to meet in Paris on 20 January to discuss the fight against IS in both Iraq and Syria.
"The battle for Mosul will have to be launched one day," Le Drian said on Thursday, referring to the major oil city that IS won from Iraqi forces in June 2014.
But he warned it would be "much more complicated" than the recent gains from IS.
"We have to make sure that the Iraqi and Kurdish forces are sufficiently battle-hardened to fight this battle," Le Drian said.
US defence chief Ashton Carter said on Wednesday that this year will see American-led assaults on Mosul and Raqqa, IS's "centre of gravity" in Syria.