Local religious leader Salah Jodeh told The Associated Press that a mosque in the village of Dir Istia was torched early on Wednesday.
He says the mosque door was set ablaze and some of the carpet was burnt.
He says graffiti sprayed on the site read: "Blood for blood, Qusra."
It's a reference to a village where Palestinians last week roughed up more than a dozen Israeli settlers who witnesses said had earlier attacked other Palestinians.
Israeli police said they were investigating.
Similar attacks in the past have been blamed on a tiny group of Israeli extremists.
BA/BA