Full-body swimsuits were banned from the beaches near the city by a new local by-law for the duration of the summer.
The court said the rule was legal under French law that prohibits people "invoking their religious beliefs to skirt common rules regulating relations between public authorities and private individuals".
The judge put the ban"in the context of the state of emergency and recent extremist attacks, notably in Nice a month ago".
Sefern Guez Guez, a lawyer for the CCIF said the group would appeal against the ruling at the highest level. "This decision opens the door to a ban on all religious symbols in the public space,” he said.
Under the law, only clothing that "is respectful to morality and secular principles, and in compliance with hygiene and safety rules” can be worn on the beach.Those caught wearing burkini risk a €38 (£33) fine.
Lionnel Luca, the mayor of Villeneuve-Loubet, a Riveiera resort, said the ban was for "sanitary reasons”.
"I was told that there was a couple on one of our beaches where the wife was swimming fully dressed, and I considered that unacceptable for "hygienic reasons” and "unwelcome” given the general situation," he told AFP.
The law came one day after an event for women wearing burkinis was cancelled in Marseille because of death threats against the organizers.