Palestinian health officials said nine Palestinians had died in Israeli airstrikes since Wednesday night. The death toll in Gaza has risen to 403 with more than 2,000 people injured.
Four Israelis have also been killed in militant mortar attacks on border towns.
The 15-member UN Security Council failed to adopt a draft UN resolution proposed by Libya and Egypt condemning the violence.
Libya's UN envoy, Giadalla Ettalhi, said Libya was seeking "a clear condemnation of the Israeli attacks which resulted in the deaths and casualties of thousands of civilians."
The draft resolution was rejected by permanent members, the U.S. and Britain, as they argued it failed to include condemnation of Hamas rocket attacks on Israeli border towns, which many Western nations say is the cause of the latest offensive by Israel.
Israel also rejected calls for a truce Wednesday evening after a meeting of the country's security cabinet.
Prime Minister Ehud Olmert said after the meeting, "If conditions develop and we believe that there could be a diplomatic solution which would guarantee better security in the south (of Israel) then we will consider it, but at the moment its not there."
Also in a telephone conversation on Wednesday between Russia's foreign minister, Sergei Lavrov, and the Palestinian president, Mahmoud Abbas, the PNA head called for "an immediate halt in the Israeli military operation from which so many have died in the Gaza Strip, and all of the border crossings into Gaza opened in line with the conditions of the international community."
Israel launched on Saturday a series of airstrikes targeting government buildings and infrastructure in Gaza in what it called "an all-out war" against Hamas.
