The massive airstrikes on Gaza began on Saturday in response to rocket and mortar fire by Hamas militants on southern Israel. Tel Aviv has mobilized up to 6,500 reservists and deployed tanks on Gaza's edge in preparation for a possible ground offensive on the coastal enclave of 1.5 million Palestinians.
Israel earlier announced that the military operation would go on until the population in southern Israel "no longer lives in terror and in fear of constant rocket barrages."
Palestinian factions have sharply increased the number of rocket and mortar barrages at Israeli towns near the border with the Gaza Strip after refusing to extend a six-month ceasefire in Gaza almost two weeks ago.
Israeli warplanes on Sunday pounded Gaza City, the northern towns of Jabalia, Beit Hanoun and Beit Lahia, the southern towns of Rafah and Ben Yunis, and two refugee camps in central Gaza, targeting Hamas government and security offices, a mosque and a TV station.
Early on Monday, an Israeli airstrike reportedly destroyed a building at the Islamic University in Gaza, a major educational facility and the "ideological cradle" of the Islamists in the enclave.
The International Red Cross said hospitals in the Gaza Strip had been overwhelmed and were unable to cope with the more than 1,400 wounded in the airstrikes.
In response to Israeli airstrikes, Palestinians have reportedly fired about 150 rockets and mortar bombs at the Jewish state, killing one Israeli man on Saturday.
"I don't know when the [Israeli] operation is going to end, I can only tell you that it is just the beginning," a spokeswoman for Israeli army told Russia's Ekho Moskvy radio.
Meanwhile, the UN Security Council has called for an immediate halt to all military actions in Gaza. The non-binding statement adopted by the 15-member body calls for an immediate halt to all violence and urges the parties to immediately stop all military activity.
Russian Foreign Minister Sergei Lavrov urged on Sunday an end to military actions in the Gaza Strip and stressed the need to allow humanitarian aid into the enclave.