Jerusalem (CNN) -- The entrance door to a century-old monastery near Jerusalem was burned away and anti-Christian graffiti was sprayed on the walls Tuesday, in what Israeli police said appeared to be a nationalistic attack.

The phrase "Jesus is a monkey" was painted on the walls of Latrun Monastery in large orange letters, as well as the words "Migron" and "Maoz Esther," referring to two illegal Israeli settler outposts in the West Bank.

Families were evacuated from the outposts over the weekend by Israeli government forces.

The Rev. Louis Wahbeh, of the 19th century monastery, told CNN that he was shocked that anyone would plan and carry out such an attack.

"This is a direct insult to our belief," he said. "We can't understand how such people can get to this low level of not respecting others, have no ethical background and don't have any human values."

He described the incident as a "price tag" attack, a term used to describe acts of vandalism by radical Israeli settlers exacting a "price" against Palestinian targets or Israeli security forces in response to actions by the Israeli government.

Such attacks have often targeted Palestinian mosques and property.

While the majority of Palestinian Israelis are Muslim, there are also Palestinian Christians living in the West Bank, Gaza, and Israel.

Police spokesman Micky Rosenfeld told CNN the attack on Latrun Monastery was a "criminal incident with a nationalistic motives."

A special investigation team has been assigned to try to identify the suspects, who fled the scene, and forensic tests are being carried out, he said.

"We are obviously looking into the possibility that extremists were involved," he said.