A top Hamas official, Khalil Abu-Leila, stated on Thursday the Palestinian Islamic group is not ready for a ceasefire with Israel, according to the Iranian Fars News Agency and following the two-day violence on both sides.
Abu-Leila added that the Ezzedine Al-Qassam Brigades, Hamas military wing, is examining an "immediate response" to the Israeli assassination of Ahmed al-Jaabari, a senior Hamas military commander, counting on the support of other Palestinian factions.
"The Israelis will probably not think of a military ground operation; they are afraid of having higher casualties within their troops," he added.
The violence erupted at around 1400 GMT on Wednesday when an Israeli air strike on a car in Gaza city led to the death of Jaabari.
The killing of Jaabari sparked furious protests in Gaza City, with hundreds of members of Hamas and its armed wing, the Ezzedine al-Qassam Brigades, chanting for revenge inside Shifa hospital.
Palestinian security sources and medics confirmed a total of four air strikes across Gaza during the late afternoon -- two in Gaza City, one of which killed Jaabari, one in northern Gaza, and a fourth in the southern city of Khan Yunis.
On Thursday, seven Gazans were killed in Israeli air strikes, as Hamas fired around 250 rockets over the border, killing three Israelis.
After Israeli attacks, the Gaza death toll rose to 15 with at least 150 people injured in 20 hours of Israeli air strikes, medics said.
In the same period, Gaza rockets killed three Israelis and injured another five in a direct hit on a residential building in the southern town of Kiryat Malachi, police said.
Israel has launched 150 military airstrikes since the eruption of violence in the Gaza strip.
The Palestinian militant group Islamic Jihad said on Thursday evening it fired a Fajr-5 rocket that reportedly hit near Tel Aviv, Israel's commercial centre city. Minutes earlier the Israeli Army Radio reported a missile strike causing sirens to go off in the city.