“We must do all we can to find our citizen,” Hollande told a press conference during a visit by Italian President Giorgio Napolitano. “I have already alerted anyone who might be in the region to take all necessary precautions.”
The kidnapped man is 61-year-old Gilberto Rodriguez Léal, who was born in Portugal but has acquired French nationality.
He crossed into western Mali from Mauritania in a car on Tuesday morning and was captured near the town of Kayes, according to the Mauritanian press agency Ami.
Foreign Affairs Minister Laurent Fabius appealed to French nationals “not to go to that part of Mali, where they put their lives and their safety in danger”.
Earlier this year one group threatened to kill the six if France intervenes militarily in north Mali.
Hollande said on Wednesday that hostage-taking would have no effect on French policy.