Najat Vallaud-Belkacem, a government spokeswoman, said Thursday there are no plans to include a "freedom of conscience" option in the law, Radio France Internationale reported.
Two days earlier, Hollande himself told a conference of mayors those who object on religious grounds might be exempt: "The law applies to all, within the limits of freedom of conscience, all the same."
Thousands of people demonstrated against gay marriage Saturday and Sunday. The Catholic Church is adamantly opposed to legalization.
On Wednesday, Hollande met with about 400 supporters of gay marriage who were protesting outside the Socialist Party headquarters. He said same-sex couples should be able to marry in every village in France.
There appears to be general agreement that mayors with conscientious objections can delegate the responsibility. But in some towns, there might be no one without objections.
"We have to make sure that, if a mayor refuses to perform such a marriage for personal reasons, he can easily delegate it to one of his deputies or even more broadly to other officials who will perform the marriage," Vallaud-Belkacem said Thursday.