France's National Assembly voted 293-222 against legalizing same-sex marriage June 14.
President Nicolas Sarkozy's ruling Union for a People's Movement party opposed the measure.
In January, France's Constitutional Court upheld the ban on same-sex marriage but said Parliament could change the law if it wanted to.
The court ruled that gay and straight couples find themselves in a "different situation" that justifies differing treatment under family law.
Polls suggest that some 60 percent of French people support letting same-sex couples marry. The nation has offered civil unions for gay couples for more than a decade, but the unions lack some of the benefits of marriage.