Pope Leo lashed out against warmongers on Saturday while calling on billions of people around the globe to embrace peace and "believe once again in love, moderation and good politics".

In one of his most passionate entreaties yet to end the raging conflict in the Middle East, the American pope said faith was needed "in order to face this dramatic hour in history together".

"Enough of the idolatry of self and money! Enough of the display of power! Enough of war! True strength is shown in serving life," Pope Leo implored in an address during a prayer vigil for peace at St Peter's Basilica.

Uttered in measured tones, as is customary for the soft-spoken head of the world's 1.4 billion Catholics, the comments by the 70-year-old Leo nevertheless marked some of the most pointed criticism yet of the wave of conflicts inflaming the globe.

"Dear brothers and sisters, there are certainly binding responsibilities that fall to the leaders of nations. To them we cry out: 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!"

As he has done in the past, the Chicago native did not cite politicians by name, and did not call out specific countries.

'Delusion of omnipotence'

Responsibility also fell to the "immense multitude" that rejects war, Leo said, urging them to build a "Kingdom of peace... in our homes, schools, neighbourhoods, and civil and religious communities."

"A Kingdom that counters polemics and resignation through friendship and a culture of encounter. Let us believe once again in love, moderation and good politics."

The pope described the Kingdom of God as a "bulwark against that delusion of omnipotence that surrounds us and is becoming increasingly unpredictable and aggressive."

It also was a place with "no sword, no drone, no vengeance, no trivialisation of evil, no unjust profit, but only dignity, understanding and forgiveness."

Leo painted a grim picture of the current state of the world, "where there never seem to be enough graves, for people continue to crucify one another and eliminate life, with no regard to justice and mercy."

Pope Leo, who was elected pontiff last May following the death of his predecessor Francis, is moderate and known as a bridge-builder. But he has been increasingly denouncing the conflicts dividing the world, most recently on Friday when he railed against the "senseless and inhuman violence" spreading across the Holy Land.

Leo has repeatedly urged de-escalation in the current US-Israeli war on Iran and the need for a diplomatic solution.