"It is evident that democracy is not in good health in today's world," he said, denouncing polarisation and partisanship.
"Ideologies are seductive. Some people compare them to the Pied Piper of Hamelin. They seduce you, but they lead you to deny yourself," he said, referring to a fairy tale where a rat catcher uses his magic powers to steal away a town's children.
He said the "crisis of democracy" afflicted various nations, but did not give any specific examples.
The pope was speaking on the day France holds a parliamentary run-off election, with the far-right National Rally (RN) expected to take the biggest share of the vote, a month after populist parties scored gains in European Union elections.
"Let us not be deceived by easy solutions. Let us instead be passionate about the common good," the pope said on Sunday, highlighting the damage caused by political "corruption and illegality".
The pope, who himself rules as an absolute monarch in the tiny Vatican state, said it was important to teach children the importance of democratic values, warning that "indifference is a cancer of democracy".