JERUSALEM (Reuters) -- A Jerusalem monastery, built on the spot where tradition holds the tree from which Jesus's cross was made, was defaced with graffiti bearing the hallmarks of Jewish extremists, police said on Tuesday.

"Death to Christians" was daubed in Hebrew on the outer walls of the Monastery of the Cross, an 11th-century fortress-like holy site situated in a valley overlooked by Israel's parliament.

Police spokesman Micky Rosenfeld said the words "price tag" were also painted overnight by the vandals, who damaged two cars parked outside the monastery in the rare attack on a Christian shrine in Jerusalem.

The slogan, used by Jewish settlers in vandalism attacks on mosques and Palestinian homes in the West Bank, refers to the retribution they say they will exact for any attempt by the Israeli government to curb settlement in the territory.

"I am a priest and I forgive," Father Claudio of the monastery, which is administered by the Greek Orthodox church, told Reuters.

Rosenfeld said police had opened an investigation.

Also on Tuesday, "Death to Arabs" was painted in Hebrew on the wall of a playground of a Jewish-Arab bilingual school in East Jerusalem.

Meanwhile in the West Bank, anti-Muslim slogans were daubed on the walls of several homes in the village of Al-Lubban al-Sharqiya overnight, a Palestinian official said, blaming Jewish settlers.

Since December, five mosques have been vandalized in attacks by suspected Jewish extremists. An ancient mosque in Jerusalem was torched on Dec. 13, and sprayed with the Star of David, "price tag," "Muhammad is a pig" and "A good Arab is a dead Arab" in Hebrew.

Settler attacks in the West Bank against Palestinians increased by more than 50 percent in 2011, according to the UN Office for the Coordination of Humanitarian Affairs.

In the West Bank, roughly 4.5 percent of the Palestinian population are Christian, a figure of around 200,000 people. In Israel, around 11 percent of Palestinians are Christian, down from 21 percent of the Palestinian population in 1949, a minority rights group says.