Pope Francis on Friday lamented a Europe he said had grown "weary" and "entrenched", and urged the continent not to see migrants and refugees as criminals.

Francis made his pointed comments in the presence of top EU leaders, including German Chancellor Angela Merkel, European Central Bank chief Mario Draghi and the presidents of the European Parliament, Commission and Council.

"What has happened to you, the Europe of humanism, the champion of human rights, democracy and freedom? What has happened to you, Europe, the home of poets, philosophers, artists, musicians, and men and women of letters?" he asked.

"What has happened to you, Europe, the mother of peoples and nations, the mother of great men and women who upheld, and even sacrificed their lives for, the dignity of their brothers and sisters?"

The pope was speaking at a ceremony in the Vatican's frescoed Sala Regia to award him the Charlemagne Prize, conferred annually by the German city of Aachen to those who have contributed most to the ideals of post-war Europe.

His comments pointed to a malaise at the heart of the European Union, which has wrestled with a long, divisive debt crisis and is struggling to absorb a vast influx of migrants and refugees, many fleeing conflicts such as Syria's civil war.

Francis called Europe "weary, yet still rich in energies and possibilities" and said it was "increasingly entrenched, rather than open to initiating new social processes capable of engaging all individuals and groups in the search for new and productive solutions to current problems."

The Argentine, the first non-European pope in 1,300 years, said desire for European unity "seems to be fading" and that "those who consider putting up fences" were betraying the dream of the founders of a modern Europe.

"I dream of a Europe that cares for children, that offers fraternal help to the poor and those newcomers seeking acceptance because they have lost everything and need shelter ... I dream of a Europe where being a migrant is not a crime," he said.

Addressing the pope, European Parliament President Martin Schulz said the migrant crisis represented "a defining challenge for Europe."

European Commission President Jean-Claude Juncker noted that the pope, who has made numerous appeals for better treatment of refugees, returned from the Greek island of Lesbos last month with 12 Syrians.

"When you take in 12 refugees — in proportion to the population of the Vatican, that is more than any EU member state — you fill our hearts with new courage," Juncker said.