Francis said he was directing a "fervent appeal" to the leaders to "show concrete solidarity toward these persons".
The situation of asylum seekers on board a ship currently stranded in Maltese waters has continued to deteriorate, with some of them now refusing food.
"In Italy, there are no more arrivals".
Another ship run by the German group Sea-Eye is carrying 17 people rescued on 29 December.
And he rammed the message home on Twitter, saying "Italy's ports are and will stay closed".
Prime Minister Joseph Muscat insisted yesterday that Malta will not let take the migrants in, warning that such an act could set a precedent and risk turning the island into a centre for asylum seekers rescued by NGO-run vessels.
Four children were being carried on one of the tiny recreational boats while the other was packed with 10 adults.
Some on board Sea Watch are being treated for dehydration caused by seasickness. Malta is also blocking the ships from docking but has allowed them to enter its waters for fresh supplies.
"It is easy to play the Christmas Saint with everyone, but then come January, February and the summer period we would be told to do the same". Thirty-two of the migrants were rescued on December 22; the others, days later.
The Netherlands and Germany have offered to take some but only if their EU partners do the same, highlighting again the European Union's long-running deadlock over sharing responsibility for migrants.
At midday prayers in St Peter's Square the Pope called on Europe to show "concrete solidarity" towards the migrants, whose fate has caused a row between Italy and Malta and opened cracks in the populist Italian government.
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