However, Hollande said France would not go further than that. "There will be no ground troops, and we will not intervene except in Iraq,” he said at a twice-yearly news conference, ruling out action against the insurgents in neighboring Syria.
Iraq is struggling to push back fighters from the extremist group who have taken over large parts of the country.
Hollande said the request for "air support" came during a visit he made to Iraq on Friday and he gave his approval at a meeting earlier Thursday of the country’s defense and security advisors.
He said the French parliament would be informed as soon as the first strikes happen, "that is to say soon.”
France is already carrying out reconnaissance flights over Iraq, which were announced at an international conference in Paris on Monday. It is also providing weapons to ethnic Kurdish fighters who are fighting the Islamic State militants, as well as humanitarian aid.
"Our goal is to pursue peace and security in Iraq by weakening the terrorists," Hollande said.
He added that French aircraft would carry out attacks "as soon as we have identified targets. That means in a short time frame. It will be air support to protect Iraqi soldiers and Kurdish peshmerga forces to reduce and weaken this terrorist group."
He was critical of "international inertia" over Syria, which he said had allowed the extremists to capture swathes of the country.
"The terrorist movement prospered in the Syrian chaos …Let’s be honest, because the international community remained inert," Hollande said. "I remember the words I spoke a year ago, after Bashar al-Assad’s regime used chemical weapons. Chemical weapons are no longer there [in Syria], but the terrorists poured into the breach and now hold large parts of territory and are now in Iraq."
Willsher is a special correspondent.