Israel says its forces raided the Palestinian military intelligence headquarters in the West Bank town of Ramallah Wednesday and detained 18 militants.
The Israeli army said the men were wanted for attacks against Israeli civilians and soldiers.
Palestinian security sources say those detained were members of the security service but also belonged to the militant al-Aqsa Martyrs Brigades group, which is an offshoot of Palestinian President Mahmoud Abbas's Fatah faction.
Palestinians say there were no injuries in the Israeli operation.
In East Jerusalem, Israeli police arrested Israeli Muslim cleric Raed Salah, after he led a protest against Israel's excavation and repair work near the Al Aqsa mosque compound.
Israeli police spokesman Micky Rosenfeld said the cleric was arrested for leading a demonstration without a permit and raising Palestinian and Syrian flags.
Salah, who leads a hard-line branch of Israel's Islamic Movement, has spearheaded the fight to stop Israel's renovation work near the holy compound in Jerusalem's Old City - that Muslims call the Noble Sanctuary and Jews, the Temple Mount.
Israel says the work is no threat to the Muslim holy site and that it is repairing a ramp damaged by a snowstorm.
Arabs and Muslim around the world say excavation work is endangering the foundation of the mosque compound - Islam's third holiest site.