The leader of 1.2 billion Catholics deplored violence around the globe as he gave his fourth "Urbi et Orbi" (To the City and The World) Christmas message from the balcony of Saint Peter's Basilica.
The 80-year-old Argentine called for guns to fall silent in Syria, saying "far too much blood has been spilled" in the nearly six-year conflict.
And he urged Israelis and Palestinians to "have the courage and the determination to write a new page of history" in his message from the balcony of Saint Peter's Basilica to a crowd of 40,000 gathered in the square below which, despite the sunny weather, was far from full.
Religious leaders from the Vatican to Bethlehem struck a sombre note on Christmas Eve, warning that war, fear and divisions lie ahead in 2017 after a tumultuous year.
As Europe ramped up security for the holiday just days after the truck attack that left 12 dead at a Berlin Christmas market, the pontiff said he hoped for "peace to those who have lost a person dear to them as a result of brutal acts of terrorism".
The attack was claimed by the Islamic State group.
In Milan, where suspected Berlin attacker Anis Amri was killed in a police shootout on Friday, there was a heavy police presence around the cathedral.
The entrance has been protected by concrete barriers since the Berlin attack.
Locals and tourists alike however are still visiting the German capital's Breitscheidplatz market, with many stopping to light a candle or lay flowers for the victims.
"It's really nice there are so many people here and it's still open," said Marianne Weile, 56, from Copenhagen.
"So even though you are really sad about what happened you can still keep Christmas. It's not like this crazy guy ruined it for everybody."
In France, 91,000 members of the security forces were deployed to guard public spaces including churches and markets over the weekend.