The Nativity Scene in St Peter's Square, he said, recalls "the sad and tragic reality of migrants on boats heading for Italy.
In the painful experience of these brothers and sisters, we see again that of the baby Jesus, who at the time of His birth did not find lodging and was born in the grotto in Bethlehem; and then he was taken to Egypt to escape the threat of Herod."
The pope said this sent "a message of fraternity, sharing, welcoming and solidarity".
The pope said in an audience for the Maltese and Trentino communities that donated this year's Nativity scene and Christmas Tree that the nativity scenes in churches and many public places, too, are "an invitation to make room in our lives and in God's society, for the many people who are in conditions of discomfort, poverty and tribulation".