Sydney native Zeynab Alshelh "could have asked herself whether the people in the area weren't still reeling from the jihadist attack that killed 86 people" in nearby Nice in July, Lionnel Luca told AFP.
"She could not just innocently come to our beaches with religious garb that is the sign of the fundamentalism that killed us," he said, calling the 23-year-old's actions "pretty indecent".
Alshelh told Australian television the bathers threatened to call the police unless she left the beach at Villeneuve-Loubet, even though a ban on the controversial full-bodied swimsuit had recently been overturned.
The burkini became a political hot potato over the summer as France gears up for a presidential election next spring.
Alshelh, a medical student, said she had travelled to Europe to show solidarity with French Muslims by wearing a burkini - invented by an Australian designer - on the beach.
Footage broadcast Sunday evening showed local bathers make disparaging gestures towards Alshelh.
Nice and about 30 other French towns banned the Islamic swimsuit after the July terror attack in which a man ploughed his truck into crowds gathered for Bastille Day fireworks in Nice.
In August, France's highest court suspended the burkini bans, declaring the swimsuit's prohibition an "illegal violation of fundamental freedoms".
