"It is time to liberate the city of Fallujah," Abadi said.
He added that all kinds of the armed forces were involved in the operation, as well as several groups allied to Baghdad.
Fallujah, in the western Anbar province, has been under Daesh control since 2014. Reports emerged recently that militants of the group, banned in countries including Russia, began killing residents attempting to leave the city. Daesh is suspected of planning to use the civilian population as human shields in case of an army siege.