The violence erupted after Israeli police raided the Al-Aqsa mosque in occupied East Jerusalem.
Hamas chief Ismail Haniyeh said Thursday that Palestinians "will not sit with their arms crossed" in the face of Israeli "aggression" against the Al-Aqsa mosque in Jerusalem.
He was speaking in Beirut after Israel blamed Palestinian militants for firing a barrage of rockets from Lebanon at northern Israel.
Haniyeh, who arrived in the Lebanese capital a day earlier, met on Thursday the heads of other Palestinian organisations as Israel threatened a military response to the rocket fire.
"Our Palestinian people and the Palestinian resistance groups will not sit idly by" in the face of Israel's "savage aggression" against Al-Aqsa, Haniyeh said in a statement after the meeting.
Israel accused Palestinian groups of firing 34 rockets from Lebanon on the Jewish Passover holiday, a day after clashes between Israeli police and Palestinians inside Islam's third-holiest site.
The violence in Jerusalem was widely denounced by neighbouring states and several Palestinian groups vowed they would respond.
In his statement, Haniyeh called on "all Palestinian organisations to unify their ranks and intensify their resistance against the Zionist occupation (Israel)".
Earlier, Israeli army spokesperson Lt. Colonel Richard Hecht said Palestinian groups were responsible for the rocket barrage.
"We know for sure it's Palestinian fire," he told reporters. "It could be Hamas, it could be Islamic Jihad, we are still trying to finalise but it wasn't Hezbollah."
The Shiite militant group effectively controls southern Lebanon and enjoys good relations with Hamas, which rules in the Gaza Strip, and the Islamic Jihad group also based in the enclave.
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