Two followers of the Islamic State group carried out the attack on a social services agency party in California.
An IS radio broadcast said two of the group's followers had carried out Wednesday's attack in Californian city San Bernardino that left at least 14 people dead and 20 injured, The Jerusalem Post cited the group as saying in its daily broadcast al-Bayan.
US citizen Syed Farook, 28, and his wife Tashfeen Malik, 27, were involved in the attack.
According to the police, "some degree of planning" was involved in the shooting spree.
Federal Bureau of Investigation (FBI) chief James Comey said on Friday that the shooting was being investigated as "an act of terrorism".
It was revealed on Friday that the wife had pledged allegiance to the IS on social media.