The law granting gay men and lesbians equality in marriage and adoption has been among the most divisive of President Francois Hollande's first year in office, pitting a predominantly liberal public in mostly Roman Catholic France against traditionalists, the far-right and many churchgoers.
Without making any specific mention of the law, Francis said the church should have a voice in political issues even in staunchly secular France.
"The church would like to offer specific contributions on profound issues ... not only in an anthropological and social circles, but also in political, economic and cultural ones," Francis said, according to a Vatican statement.
Parliamentarians should legislate according to "a spirit, a soul, that does not reflect only the fashions and ideas of the moment", he said.
The passage of the law prompted a massive protest march in Paris and has come to embody wider discontent with Hollande.
The pope met the French delegation of parliamentarians, who are members of a "Friendship Group" with the Vatican, on the same day that thousands took part in Rome's annual "Gay Pride" parade.
One of the men marching in the parade - wearing a pink wig and heart-shaped sunglasses - said gay marriage would never be legal in Rome as it is in Paris.
"The Catholic Church is too powerful in Italy," Massimo Marra told Reuters.