Far-right graffiti was found spray painted in Muslim and Christian cemeteries in Jaffa, police said on Saturday night.
The messages "price tag" and "death to Arabs" were written on the tombstones.
Police denied media reports that some 25 graves were damaged in the incident.
"We have not seen any smashed stones," a Tel Aviv police spokeswoman told The Jerusalem Post.
"An investigation is underway," she added.