An ultra-Orthodox news website quoted officials from the United Torah Judaism alliance, part of Netanyahu's coalition, as saying that eating in a non-kosher restaurant was unacceptable for a prime minister of the Jewish state.
It said he had eaten over the weekend at Enoteca Pinchiorri, a restaurant Michelin calls one of Florence's “temples of gourmet dining”.
United Torah Judaism holds seven seats in parliament, where Netanyahu's coalition has only a one-seat majority following March elections.
An official in the prime minister's office confirmed that Netanyahu “was invited to a restaurant by the Italian prime minister (Matteo Renzi), but he did not eat forbidden foods”.
“This is also the procedure he always follows during his trips abroad,” the official said. The Kikar Hashabbat site quoted officials from United Torah Judaism as saying that the prime minister should have acted with more sensitivity.
It is not the first time Netanyahu has faced scrutiny over a restaurant visit.
Last year, the same website criticized him for eating in a non-kosher restaurant in New York with Sheldon Adelson, the American billionaire who owns Israel Hayom, a free daily that has supported Netanyahu.
Jewish dietary law bars consumption of certain foods such as pork and shellfish, and also prohibits the mixing of meat and dairy products.
Rabbits are considered unclean because they do not have cloven hooves, while anything that crawls on its belly is prohibited. Animals must be slaughtered ritually under the supervision of a rabbi.