The United States, Russia, the European Union, and the United Nations -- the so-called Quartet of Middle East peace mediators -- have called on the Palestinians and Israelis to halt "provocative actions" in a bid to end renewed violence.
In a statement, the group expressed concerns over the escalation and called for calm.
U.S. Secretary of State Hillary Clinton, Russian Foreign Minister Sergei Lavrov, and UN Secretary General Ban Ki-moon met at UN headquarters in New York on the sidelines of a UN Security Council meeting. Quartet envoy Tony Blair and European Affairs foreign policy chief Catherine Ashton took part in the discussion by teleconference.
At least 23 Palestinians have been reported killed in Israeli air strikes since clashes began four days ago.
Israel says it is responding to scores of rocket attacks from Gaza.
With AFP and dpa reporting