Israel is refusing to open its border crossings with the Gaza Strip in response to a Palestinian rocket attack which breached a fragile ceasefire agreed last week.
Earlier world powers called for calm in the Middle East as renewed violence threatened to wreck the Gaza truce.
The EU, the United Nations, Russia and the United States, meeting to discuss a 155 million Euro aid package for the Palestinians, appealed for peace.
EU foreign policy chief Javier Solana said: “I think that everybody in Israel and Palestine will have to be aware of the difficulties of the moment. To maintain the calm will be the most beneficial for everybody.”
The call came in the wake of a rocket attack on the Israeli town of Sderot where residents looked on in anger.
“So it fell on his house now, too. Ceasefire? What ceasefire?” asked one woman.
Militants in the Hamas-controlled Gaza Strip fired at least two rockets into southern Israel after Israeli troops killed two Palestinians in the West Bank city of Nablus.
The Quartet of world powers, who were meeting in Berlin, also reiterated calls for Israel to freeze all settlement building, another stumbling block on the road map to peace in the region.