The United States has blocked an urgent UN Security Council meeting originally set for Friday on the new flare-up between Israel and the Palestinians, diplomats said.

"There will be no SC meeting tomorrow," said a spokesman for the UN delegation of China, which currently presides over the council.

"The United States did not agree with a videoconference tomorrow," one diplomat said.

Another diplomat said the US wants the meeting put off until Tuesday, which would undermine the sense that it is of an urgent nature.

Meetings like this via videoconference require the support of all 15 members of the council.

In its statements this week on the Mideast crisis, the US has said Israel has the right to defend itself from rocket attacks launched by the Islamist movement Hamas from the Gaza Strip, but it also called for de-escalation of the conflict.

Washington also urged Israel to do everything it can to avoid civilian casualties.

Israel deployed additional troops to Gaza's border Thursday as the military conflict with Palestinian Islamists raged on.

In Gaza, 83 people were reported killed since Monday -- including 17 children -- and more than 480 people wounded as heavy bombardment has rocked the crowded coastal enclave and brought down entire tower blocks.

Inside Israel, seven people have been killed since Monday, including one six-year-old, after a rocket struck a family home.