The Pope delivered his “Urbi et Orbi” message to thousands of pilgrims who gathered in St Peter’s Square at the Vatican.
Francis said the bombing, which killed more than 100 people near the city of Aleppo was “the latest vile attack on fleeing refugees”.
He also spoke against “old and new” forms of slavery and discrimination.
“May God] sustain the efforts of those who are actively working to bring comfort and relief to the civilian population in beloved Syria, who are greatly suffering from a war that does not cease to sow horror and death,” he said.
In the latest attack, a vehicle filled with explosives targeted buses carrying evacuees from besieged, government-held Syrian towns.
At an earlier vigil, Francis spoke of migrants’ pain, and criticised “paralysing and barren bureaucracies that stand in the way of change”.