Palestinian President Mahmoud Abbas urged Western powers on Thursday to intervene after Israeli strikes on the Gaza Strip killed four Palestinians.

He called on the West "to immediately intervene to stop this aggression", the official Wafa news agency reported.

Abbas also urged Palestinian militants not to give Israel an excuse to hit Gaza. The flareup of violence followed an attack on an Israeli school bus in which an anti-tank missile fired from Gaza wounded two people, drawing a swift Israeli response.

The Islamist Hamas movement which rules Gaza and opposes the peace-seeking policies of Abbas said it was responsible.

"The escalation against Gaza Strip is condemned and rejected," Abbas said. He held "swift contacts with a number of European parties and other international partners to halt this escalation", Wafa added.

Palestinian medics said at least 30 people were injured in three hours of attacks by Israeli forces. Firing tapered off after nightfall.

A teenage Israeli boy on the bus was seriously wounded and its driver also was injured. A 4-year-old Palestinian girl was injured in the densely populated Gaza Strip.

"We hope this situation will be contained, but we will not shy away from taking all the necessary action, offensive and defensive, to protect our country and to protect our citizens," Israeli Prime Minister Benjamin Netanyahu told a news conference during a visit to Prague.