Pope Francis and US President Joe Biden discussed the Israel-Hamas conflict and other wars in a telephone conversation on Sunday, the Vatican said.
The conversation lasted about 20 minutes and "focused on conflict situations in the world and the need to identify paths to peace," the Vatican said.
Israel is preparing for a ground assault on Gaza, two weeks after a Hamas attack in Israel that killed 1,400 people.
Earlier in the day, Francis told crowds in St Peter's Square he was deeply saddened by the "grave situation in Gaza," where an Anglican hospital and a Greek Orthodox church had been bombed.
"Brothers, stop," Pope Francis said.
Biden, who is a Catholic, said on Saturday that he was talking to the Israelis when asked if he was encouraging them to delay an invasion of Gaza.
Hamas said it took about 200 hostages during the incursion into communities and military bases in southern Israel.
The pope has several times called for the release of hostages.