A French army source in Mali said: "The operation was carried out on Wednesday night around 100km north of Timbuktu.
"Eleven terrorists were killed and one French soldier was wounded."
A source at the Malian defence ministry in Bamako said French forces were carrying out operations in the region against Islamist militants, using air and ground troops. A French-led offensive last January drove out Islamist militants who had seized control of northern Mali. However, some fighters linked to al Qaeda are still holding out in pockets of territory in a north, a year after the offensive.
The groups have stepped up attacks in recent months, targeting the northern cities of Kidal, Timbuktu and Gao. Two French journalists were killed by Islamists in Kidal in November.
French and Malian military officials said threats of militant attacks on Timbuktu and Kidal remained real.