A Sky News report says police estimate that 7,000 people showed up to protest against the measure in Bordeaux, while organizers say their count was closer to 20,000. A counter-protest by same-sex marriage supporters drew 3,000, police told Sky.
In Lille, several thousand reportedly took to the streets with signs that read, "Daddy and Mummy: there's nothing better for a child," and "We all came from a mother and father," the report says.
Smaller demonstrations were also recorded in Reims, Nancy and Le Mans.
These marches follow back-to-back protests last month against the measure that drew thousands onto the streets of Paris and other cities. An even bigger rally is expected to take place in Paris Jan 13.
Meanwhile, some 2,000 mayors have signed a petition asking that they be exempted from officiating at gay marriages should the government's measure pass.
Still, polls show that most French people support gay marriage, Sky reports.
Last month, Marisol Touraine, minister of social affairs, said that while she respects protesters' concerns, the government will not scrap its bill, which is set for debate in the National Assembly Jan 29.
A Guardian commentary on the issue says in part that the debate about gay marriage has ignited "a new wave of homophobia" in France, where "anti-gay activists and elected officials from both sides of the political spectrum routinely compare the 'sins' of same-sex marriage to polygamy, or even incest."
Romain Burrel writes, "if our politicians are that reactionary, the church has something to do with it. Even if France is the country that gave birth to the concept of laicité, which advocates strict separation between the church and state, our country is still one of the oldest daughters of the Catholic church – which is vehemently against same-sex marriage, and rabidly opposing adoption by gay parents. The archbishop of Paris and one of the highest dignitaries of the French Catholic church, Monsignor André Armand Vingt-Trois, defined same-sex marriage as a "pure deception."
But according to Burrel, in the midst of the intolerance and jibes, he sees France waking up to the reality of gay couples, the presence of which is all over the media.