Police said they haven't linked Wednesday's blast to the publication by a French satirical publication of caricatures of the Prophet Muhammad, Jewish Telegraphic Agency reported.
Reports conflicted about whether the blast was from a grenade or a package left at the store in Sarcelles, known as "Little Jerusalem" because of its large Jewish population.
Richard Prasquier, president of an umbrella group representing Jewish communities in France, told a French broadcaster two men tossed an explosive device into the shop.
"I have no reason to doubt the anti-Semitic character of this action," Prasquier said.
Yves Jannier, state prosecutor in the Val d'Oise region that includes Sarcelles, said investigators were collecting evidence and warned against drawing any conclusions, European Jewish Press reported.
"We'll need to analyze, quantify and measure all these elements, such as to know perhaps the type of explosives used," Jannier said. "But for now, we should avoid any extrapolation or hasty conclusions."