Addressing crowds in St. Peter's Square at the Vatican, Francis, who decried the suffering of migrants at the border between Mexico and the United States this month, said on Sunday the "refugee drama" was always in his prayers.
"Greece and other countries on the front line are giving these people generous help, which needs the collaboration of all countries. A response in unison could be effective and distribute the load fairly," the pontiff said.
"To do this, we need to push decisively and unreservedly in negotiations," he added.
Greece has been inundated with refugees and migrants after Balkan countries shut their borders and Austria restricted entry for the hundreds of thousands aiming for Europe, which is in the second year of its biggest migration crisis since World War Two, Reuters reported.
Francis welcomed a cessation of hostilities deal in Syria, where five years of civil war have killed more than 250,000 people and driven 11 million from their homes, swelling the tide of refugees.
"I have greeted with hope the news about a stop to hostilities in Syria, and I invite everyone to pray that this glimmer can give relief to the suffering population, enable necessary humanitarian aid and open the way to dialogue and longed-for peace."
Guns fell mostly silent in Syria when the truce came into effect on Saturday, but reports of violations have come from both sides.