Unlike Saturday's rallies, which unfolded in a family-friendly atmosphere, Sunday's demonstration in the capital was marred by accusations that journalists covering the rally and topless counter-protesters dressed as nuns had been roughed up.
Thousands of people attended the rally, organised by the conservative Catholic group, Civitas, whose stated aim is to "re-Christianise" France.
French feminist writer and columnist Caroline Fourest said about a dozen topless activists from the Ukrainian-based women's movement Femen had shown up to the protest partially dressed as nuns and chanting "humorous" slogans.
"When they moved toward the demonstrators, some of them ran after them, raging," Fourest said in a phone call with AFP from a police wagon, where the women had been taken for their safety.
She claimed the women were hit by their pursuers, who also lashed out at journalists filming the scene.
Several photographers were roughed up, an AFP photographer said. The local police station said officers had made five arrests.
French Socialist party first secretary Harlem Desir denounced the aggression as "stupid".
Among the banners being held by demonstrators was a large one reading: "France needs children, not homosexuals."
The protesters included several young people wearing cassocks, a Christian clerical garment. Others waved the French flag and banners depicting the Christian cross and other emblems.
"Our objective is to wage a real battle to protect the family and child," Civitas official Alain Escada said.
He claimed gay marriage was "a Pandora's box" that would let others demand extended marriage rights, including polygamists and incestuous people.
Civitas claims 1200 members and a network of about 100,000 supporters.
Social Affairs Minister Marisol Touraine said she respected demonstrators' concerns but the government was not scrapping its bill.
