Lebanon was drawn into the Middle East war last month as Israel pursues the Iran-backed Hezbollah group, with Lebanese authorities reporting more than 2,000 people been killed in Israeli strikes.

"I am closer than ever, in these days of sorrow, fear, and unconquerable hope in God, to the beloved Lebanese people," the pope told the crowd at St Peter's Square following his Regina Coeli prayer.

"The principle of humanity, inscribed in the conscience of every person and recognised in international law, entails the moral obligation to protect the civilian population from the atrocious effects of war," he said.

As he has done in the past, without citing names, the American pope called on the parties involved to seek a peaceful resolution.

The comments from the 70-year-old pontiff came as Iran and the United States failed to strike a deal during talks in Pakistan to end the war in the Middle East.

On Saturday during a prayer for peace, the soft-spoken Leo made one of his most pointed criticisms yet of the war, imploring leaders to end the violence.

"Stop! It is time for peace! Sit at the table of dialogue and mediation, not at the table where rearmament is planned and deadly actions are decided!" he said.

"Enough of the idolatry of self and money! Enough of the display of power! Enough of war!"

The leader of the world's 1.4 billion Catholics has repeatedly urged de-escalation in the current US-Israeli war on Iran and a need for a diplomatic solution.

On Monday, the pope heads to Algeria for the start of an 11-day tour in Africa where he will bring a message of bridge-building with the Islamic world.