President Francois Hollande vowed the state would protect French Jews with all its force as he led a ceremony Tuesday at a Jewish cemetery where hundreds of graves were vandalised.
"I know some are asking if they can live in peace in their country, and ask who will protect them against those who wish them harm," Hollande said at the ceremony in Sarres-Union in the eastern Alsace region.
"One more time, I want to give the Republic's response -- that it will protect you with all its force."
He was speaking at a Jewish cemetery where some 300 tombs and graves were defaced and damaged last week.
"You get the impression that an army has passed through here," said the chief rabbi of Strasbourg, Rene Gutman, as he visited the cemetery.
"Must we put soldiers in front of cemeteries?" the president asked in a speech after surveying the overturned gravestones.
"How do we understand the unnamable, the unjustifiable, the unbearable?" Hollande said. "This is the expression of the evils eating away at the Republic."
Five youths aged 15 to 17 have been taken into custody over the incident.
Prosecutors say there is no indication they were specifically targeting the Jewish community, with one boy reportedly claiming they were unaware the cemetery was for Jews.