France and the United States will present a "common front" in the fight against a "shared threat", the French presidency said Saturday after Francois Hollande spoke by phone with US President Barack Obama to express his condolences over the shooting in California.

"The two presidents reaffirmed the conclusions of their discussions in Washington and Paris in recent days, that in the face of a shared threat, France and the United States will form a common front with their allies by uniting their efforts and their means," the Elysee Palace said in a statement.

It added that Hollande had expressed his country's "solidarity and emotion" after the San Bernardino rampage on Wednesday, which left 14 dead and is being investigated as an act of terrorism.

The Islamic State group has praised the perpetrators behind the shooting but stopped short of explicitly claiming the attack.

ISIS claimed responsibility for last month's gun and suicide bombing attacks in Paris that killed 130 people, prompting Hollande to call for stepped up, global efforts in the fight against the miltants.