UN Secretary General Kofi Annan has called for a full investigation, saying he was "deeply disturbed" by the deaths.
The Arab has League condemned the attack as "unacceptable terrorism."
The foreign ministers of the Gulf Cooperation Council, made up of six Arab monarchies, denounced what they called Israel's "criminal acts."
Russia - a member of the international quartet mediating in the Middle East peace process alongside the European Union, the UN and the US - said it was deeply shocked by Israel's "unacceptable" and disproportionate" use of force.
France also condemned the air raids as "disproportionate".
Spain expressed "opposition to the use of force as a means of solving the Israeli-Palestinian conflict".
Jordan has called the attack a crime.
"The Israeli escalation against the Palestinians does not help in creating climates of trust between the two sides and will increase tensions," the official Petra news agency quoted government spokesman Nasser Jawdeh as saying.
The Egyptian government said the shelling was unacceptable.
Egypt's Muslim Brotherhood, the largest opposition bloc in
parliament, denounced the deaths as a "new massacre".
AFP