Organizers 500,000 individuals took part in the protests near the Eiffel Tower, but put police said 120,000 people took part, the BBC reported.
They carried signs that read, "We don't want your law, Francois" and "Don't touch my civil code."
Organizers made it clear that their movement is not directed at homosexuals and is non-religious and non-political, despite their support from the Catholic Church and right-wing politicians.
BBC said France already allows civil unions between same-sex couples, and President Francois Hollande promised during his campaign to extend those rights.
BBC said a poll of almost 1,000 people indicated 56 percent of people support gay marriage, while 50 percent disapproved of gay adoption. The details of the poll were not reported.
Earlier polls indicated stronger support for gay marriage, BBC said.