Paris was to deploy some 500 police along the River Seine on Thursday, at the start of a beach attraction dedicated to Tel Aviv that is expected to draw protests from anti-Israel groups.
The city authorities' decision to devote one of its hugely popular "Paris plages" (Paris beaches) days to celebrate Tel Aviv has sparked uproar among some left-wing politicians and pro-Palestinian groups.
Protesters have vowed to celebrate a "Gaza beach" nearby and police are bracing for potentially violent clashes.
Police will search beach bags before and after the 12-hour event with security levels still on top alert after the January Charlie Hebdo attacks that left 17 dead.
City authorities have resisted pressure to scrap the event and Prime Minister Manuel Valls has voiced his "full support" for the initiative.
But a handful of councilors from the left-wing PG party and the communist party have urged the event's cancellation, seeing a tacit support of Israel's policy towards the Palestinians.
The deputy mayor of Paris, Bruno Julliard, warned that the controversy risked dampening the event, during which authorities pour sand onto the banks of the Seine and set up food and drink stalls.
"We wanted a festive atmosphere with fun, free shows, concerts, food trucks and the like," he told French radio.
"In fact, there will be a significant police presence, so it will maybe be a bit less festive than we expected," he added.
He stressed that the difference had to be drawn between "the city of Tel Aviv, its citizens, its progressive mayor" and "the Netanyahu government policy that we condemn."
France is home to Europe's largest Jewish community and the largest number of Muslims on the continent although its secular laws mean that no precise figures are available.
