The statement was made during his speech at the European Parliament in November 2014, when he harshly criticized the state of European society and said that Europe "gives the impression of something aged and emaciated."
The head of the Catholic Church also said he urged Europe to get rid of the fear and loneliness and revive its leadership. But the German leader apparently perceived his words as insulting.
"She was a bit angry about the fact that I compared Europe to a barren woman, incapable of producing children," the pontiff said in an interview with Corriere della Sera.
During the call, the Pope told Merkel that Europe can still have children, because it "has strong and deep roots". He also added that "in the darkest times" Europe has always demonstrated "unexpected resources" and explained that his forecasts about Europe's future were in no way pessimistic.