He said there had been heavy fighting in the Ifoghas mountains, where members of al-Qaeda in the Islamic Maghreb (AQIM) were thought to be hiding.
Mr. Hollande also praised Chadian troops for their efforts in the same area, BBC says.
13 Chadian soldiers and some 65 militants were killed in clashes on Friday, according to the Chadian army.
Chad’s government has promised to deploy 2,000 troops as part of the African-led International Support Mission to Mali (Afisma).
Speaking in Paris on Saturday, President Hollande said “heavy fighting” was taking place in the far north of Mali, near the Algerian border.
“This is the final phase of the process since it is in that massif [the Ifoghas mountains] that AQIM forces have probably regrouped,” he said.
“Our Chadian friends launched an attack yesterday which was very harsh with significant loss of life,” Mr. Hollande added. “I want to praise what the Chadians are doing.”
The latest fighting was between Islamists militants and ethnic Tuareg in the In-Khalil area, near the border town of Tessalit.