The conflict between Israel and Hamas is escalating by the hour, with the Israeli military preparing to call up as many as 30,000 reservists.
Israeli warplanes are continuing attacks on the Gaza Strip after rockets were fired into Israel by Palestinian militants.
Sirens have been heard over the city of Tel Aviv, Israel's commercial capital, for the first time in nearly 20 years.
Long range missiles made in Iran were fired from Gaza on Thursday, but there were no casualties.
One of the rockets landed on the southern outskirts of Tel Aviv while the other landed in the sea.
The ABC reports other rockets have been fired from Gaza towards towns and settlements in southern Israel.
Two days of Israeli air strikes have killed 19 Palestinians, including seven militants and 12 civilians, among them six children and a pregnant woman while a Hamas rocket has killed three Israelis in the town of Kiryat Malachi.
Israel said on Thursday that more than 70 targets within Gaza had been hit in airstrikes.
Earlier this week, Israel killed Hamas' military mastermind, Ahmed Al-Jaabari, in a precision air strike on his car.
In a broadcast after the rockets were fired at Tel Aviv, Defence Minister Ehud Barak said: "This escalation will exact a price that the other side will have to pay."
Prime Minister Benjamin Netanyahu says he hopes Hamas understands that Israel will do whatever it takes to defend its people.
Mr Netanyahu's office would not comment on the possibility of a ground offensive but a spokesperson says srael has a right to defend itself.