Francis, during a visit to a city in central Italy that was severely damaged by a string of earthquakes in 2016, said he was worried by the ramifications of the attacks.
"I invite everyone to use the instruments of diplomacy to resolve the complex problems of the conflicts in the Middle East," he said.
"I renew a heartfelt appeal to the international community to make every possible effort to favor dialog and peace," he said after saying a Mass for several thousand people.
Washington, already embroiled in a standoff with Iran over its nuclear program, has blamed Tehran for the attacks. Iran has denied any involvement.
During his one-day visit to Camerino, a university city in Italy's central Marche region, Francis wore a white fire fighter's helmet as he visited the cathedral, which was severely damaged in the quake.
He prayed before a statue of the Madonna whose face was cut in half by falling debris and also visited several families living in temporary, pre-fabricated housing and entered the city's "red zone," which is off-limits because of the risk of more collapses.