Pope Francis has urged Israeli and Palestinian leaders to show courage to seek peace in the Middle East.
The Pope was speaking after hosting joint prayers at the Vatican with Israeli President Shimon Peres and his Palestinian counterpart, Mahmoud Abbas.
Mr Peres said making peace was a "holy mission". Mr Abbas spoke of a "comprehensive and just peace".
The Pope has stressed that the Vatican is not seeking to get involved in peace negotiations between the two sides.
The talks collapsed in acrimony in April.
Pope Francis had invited the pair on his recent trip to the Holy Land.
The three men, and the spiritual head of the Orthodox Christians, Patriarch Bartholomew, were driven together to the Vatican gardens.
The Pope then sat between the two presidents as a chamber orchestra played.
"Peacemaking calls for courage, much more so than warfare," Pope Francis said.
"Instil in our hearts the courage to take concrete steps to achieve peace," he prayed.
The Israeli president said: "It is within our power to bring peace to our children. This is our duty, the holy mission of parents."
"O Lord, bring comprehensive and just peace to our country and region so that our people and the peoples of the Middle East and the whole world would enjoy the fruit of peace, stability and coexistence," Mr Abbas said.
The three men then shook hands and planted an olive tree.
Vatican officials have insisted there is no ulterior political motive behind Pope Francis' invitation and no concrete initiatives are expected.
Analysis by Alan Johnston, BBC News, Rome
Pope Francis has said he'll make no attempt to mediate between his Israeli and Palestinian visitors. He says that's a job for diplomats.
The Pope is trying something a little different here - a spiritual approach. He hopes that the prayers in the calm of the Vatican gardens might just improve the atmosphere between the two sides. And that that in turn might perhaps lead to the opening of new possibilities for peace.
For Pope Francis, the power of prayer has the capacity to change everything.
But those most familiar with the harsh realities of the Israeli-Palestinian dispute are likely to look on with some considerable scepticism.
Mr Peres and Mr Abbas know each other well - they signed the Oslo peace accords in 1993.
The Israeli president occupies a largely ceremonial position and has no formal role in peace talks. He is due to leave office at the end of this month.
But officials say that the Israeli government backs his trip to the Vatican and Prime Minister Benjamin Netanyahu has been in "constant contact" with him.
Sunday's prayer event was organised in minute detail and comprised Jewish, Christian and Muslim prayers.
The holding of such a ceremony is likely to add to the Pope's reputation, correspondents say, as someone who is unconstrained by diplomatic and theological niceties when it comes to advancing the causes of diplomacy and peace.
The BBC's David Willey in Rome says the pontiff has often bypassed the formal machinery that normally conducts Vatican foreign policy.