ISRAELI WAR CRIMES CONTINUE- "Obama said he was "deeply concerned" about civilian losses, with the Palestinian death toll now over 300."
On Saturday, an early morning air strike outside a mosque in the southern town of Khan Younis killed seven people.
In the north, where there has been heavy tank shelling, a family of eight - including four children - was killed, according to local health officials.
UN Secretary General Ban Ki Moon will arrive in the region on Saturday to try to mediate between Israel and Hamas.
Mr Ban's visit would aim to help Israelis and Palestinians "end the violence and find a way forward", UN political affairs chief Jeffrey Feltman said.
"Israel has legitimate security concerns, and we condemn the indiscriminate rocket fire from Gaza into Israel. But we are alarmed by Israel's heavy response," Mr Feltman added.
Mr Netanyahu has warned of a "significant expansion" of the offensive but Hamas, the Palestinian group that controls Gaza, said Israel would "pay a high price" for the invasion.