A monument which marked the site of a synagogue torched by the Nazis was attacked by vandals on Saturday.
Authorities in Strasbourg said it was found pushed off its base and left lying damaged on the ground.
The memorial stood in tribute to a shul which was set on fire by the Hitler Youth in 1940.
Photographs published by regional newspaper Dernieres Nouvelles d'Alsace showed the damage to the memorial stone.
Officials said the damage was discovered in the French city on Saturday morning.
Strasbourg mayor Roland Ries said it was “a new antisemitic act” adding the stone "must weigh 300 or 400 kilograms."
Mr Ries said. "It wasn't pushed off by a single individual."
Writing on Facebook after visiting the memorial on Saturday, Mr Ries said: “I say once again: Enough!"
It comes following a spate of antisemitic acts in France in recent months.
Last month, 80 Jewish gravestones were spray-painted with swastikas in a Jewish cemetery close to Strasbourg.
The Jewish graves were vandalised in a small Alsace town.
Photographs from the scene showed swastikas and antisemitic graffiti daubed on tomb stones.