"The world cannot tolerate terrorism, we must defeat them militarily and discredit the extremist ideology that forms the basis of their existence!" he wrote on Twitter.
A bomb explosion tore through the Rawda mosque in Egypt's restive North Sinai province, and then armed attackers raked fleeing worshipers with gunfire.
State media put the death toll at 235. The mosque, located roughly 40 kilometers west of the North Sinai capital of El-Arish, was frequented by Sufis.
The US president was spending the Thanksgiving weekend in Florida.