Israeli forces have launched a major aerial offensive against Hamas targets in the Gaza Strip region as part of its "Operation Protective Edge".
Calling up about 1,500 reservists in preparation for further escalation, the Israeli Defence Forces (IDF) said: "Hamas will not be safe as long as it continues to threaten the lives of Israeli civilians."
Palestinians say at least nine people, suspected militants, were killed in the Israeli airstrikes which hit about 50 targets, mostly in the centre of Gaza.
The midnight response came after a barrage of rocket fire from the Gaza region fell into Israel. More than 85 rockets were fired, said the IDF.
Meanwhile, the defiant Islamic militant outfit vowed to keep up its offensive and warned that they would target Tel Aviv.
A spokesperson for the Hamas military wing, al-Qassam Brigades, said Tel Aviv residents should expect rockets in the next few hours and experience "an earthquake".
"This is not the time for quiet. We have a bank of various targets. An Iron Dome [missile battery] will be needed in every Israeli home," said spokesperson Fawzi Barhoum, according to reports.
Meanwhile, US President Barack Obama has urged both sides to avoid conflict, reaffirming Washington's commitment to a peaceful resolution of the Israeli-Palestine conflict.
"Peace is necessary because it's the only way to ensure a secure and democratic future for the Jewish state of Israel. While walls and missile defence systems can help protect against some threats, true safety will only come with a comprehensive negotiated settlement.
"Reaching a peace agreement with the Palestinians would also help turn the tide of international sentiment and sideline violent extremists, further bolstering Israel's security," Obama wrote in an op-ed piece in Israel's Haaretz daily.