In his Easter address before a huge crowd he said: "We ask you, Lord Jesus, to put an end to all war and every conflict, whether great or small, ancient or recent,"
Francis celebrated Mass to a crowd of at least 150,000 in St Peter's Square and beyond, weaving his message around the suffering of people across the globe.
He asked God to "help us to overcome the scourge of hunger, aggravated by conflicts and by the immense wastefulness for which we are often responsible".
Since his election as the first non-European Pope in 1300 years, Argentininian Francis has made defence of the poor his hallmark, often criticising developed nations and the excesses of capitalism.
The 77-year-old prayed for protection of those who are particularly vulnerable to exploitation and abuse - women, children, the elderly and immigrants.
He called on the international community to "boldly negotiate the peace long awaited and long overdue" in Syria, where more than 150,000 people have died in civil war, a third of them civilians.
"We pray in a particular way for Syria, that all those suffering the effects of the conflict can receive needed humanitarian aid and that neither side will again use deadly force, especially against the defenceless civil population," he said.
Francis asked God to "enlighten and inspire" initiatives to bring peace in Ukraine and asked for an end to violence in Iraq, Venezuela, South Sudan and the Central Africa Republic.