"There were 19 killed," Fabius said on Europe 1 radio.
The French offensive targeted Al-Qaeda in the Islamic Maghreb (AQIM) fighters north of the desert caravan town of Timbuktu.
France launched a military intervention in January that evicted Islamist rebels from northern Mali towns they had taken in the wake of a coup in Bamako last year, including Timbuktu, Gao and Kidal.
But the jihadists have continued to launch periodic strikes on French, Malian and African peacekeeping forces.
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Their deaths and the continuing insecurity overshadowed a second round of parliamentary elections that took place today.
The French offensive this week was a "huge military operation, the largest in the Timbuktu region since the major northern cities were retaken by allied forces," an African military source in Timbuktu said earlier.
Fabius said that while there was still some unrest in northern Mali, the country as a whole had been "secured".