For the second consecutive day, Vatican media weighed in with forceful editorials restating the Roman Catholic Church's unequivocal opposition.
"It is clear that in Western countries there is a widespread tendency to modify the classic vision of marriage between a man and woman, or rather to try to give it up, erasing its specific and privileged legal recognition compared to other forms of union," Father Federico Lombardi, said in a tough editorial on Vatican Radio.
Voters in the U.S. states of Maryland, Maine and Washington state approved same-sex marriage on Tuesday, marking the first time marriage rights have been extended to same-sex couples by popular vote.
Same-sex unions have been legalized in six states and the District of Columbia by lawmakers or courts.
Lombardi's editorial on Vatican Radio, which is broadcast around the world in some 30 languages, called the votes myopic, saying "the logic of it cannot have a far-sighted outlook for the common good".
Vatican vows to fight gay marriage after gains in U.S., Europe
The Vatican, reacting to strong gains for gay marriage in the United States and Europe, on Saturday pledged never to stop fighting attempts to "erase" the privileged role of heterosexual marriage, which it called it "an achievement of civilization".