Israeli Defence Minister Ehud Barak condemned on Monday "assaults by hooligans" disrupting Palestinian olive picking in the occupied West Bank, but said Israeli security could not protect the harvesters everywhere.

Israel has deployed forces in a "supreme effort" to let the harvest proceed despite attacks by Jewish settlers in some olive groves this month, Barak told Israel's Army Radio.

Palestinian President Mahmoud Abbas told reporters on Sunday that the disruption of the harvest was "a dangerous Israeli escalation". He pledged to fund the plantings of a million trees to make the rocky West Bank terrain greener.

Asked about Abbas's remarks, Barak said "the assaults by hooligans in the area ... deserve condemnation."

"But there are hundreds of sites where the olive harvest takes place and it isn't possible to be everywhere," Barak added. He also urged Palestinians to coordinate with Israeli security forces to ensure they could harvest olives safely.

Olives are an important cash crop for thousands of Palestinians among the three million Palestinians living in the territory captured by Israel in a 1967 war.

About 300,000 Jews live in settlements built by Israel in the territory, an issue that has bedevilled Western-backed peace talks for decades. Palestinians say settlements rob them of land they need for a viable state.

Israeli soldiers intervened to chase away dozens of settlers who assaulted olive harvesters near the West Bank town of Qalqilya on Sunday, Palestinian witnesses said.

But another harvest near the West Bank town of Hebron was called off on Saturday after several settlers assaulted two photographers and a foreign peace activist. Police restored order by forcing everyone to leave the area.