Israeli leaders said at least 700 rockets had been fired from Gaza since Wednesday, The Jerusalem Post reported. A rocket aimed at Tel Aviv, Israel's second-largest city, was intercepted by an Iron Dome battery.
Overnight, Israel struck the Hamas headquarters in Gaza.
Egyptian President Mohamed Morsi met with Turkish Prime Minister Recep Tayyip Erdogan in Cairo, The Washington Post said. The Arab League met in Cairo Saturday with some leaders urging Egypt -- which has had a treaty with Israel for more than 30 years -- to reconsider its position.
Erdogan spoke at Cairo University, condemning the Israeli airstrikes on Gaza.
"If Turkey and Egypt unite, everybody will be singing of peace in the region," he said. "And if we stick together, the region will no longer be dominated by crying and weeping."
Israel says it destroyed the headquarters of Hamas leaders Saturday in a wave of airstrikes. Since Israel killed Hamas' military chief Wednesday, about 40 Palestinians and three Israelis have died, the BBC reported.
Overnight strikes are reported to have killed at least eight Palestinians, including three members of Hamas' military wing, the Izz al-Din al-Qassam Brigades.
An estimated 200 sites in Gaza were hit overnight, said Israeli military spokeswoman Avital Leibovich. Targets included rocket launchers, weapons warehouses and smuggling tunnels between Gaza and Egypt.
Strikes on Gaza came in waves as militants launched more rockets into Israel. Gaza City was hit with a series of large explosions about 3 a.m. local time, followed by another string of attacks about 2 hours later in which a number of Hamas office buildings were hit.
The Palestinian Cabinet headquarters and Prime Minister Ismail Haniya's office were leveled. The Ministry of the Interior, a police compound and a Hamas training facility also were targeted, CNN reported.
Israeli tanks and armored vehicles Saturday joined Israeli soldiers gathering near the Gaza border, raising the specter of a ground invasion. The Israel military said 30,000 troops were being mobilized and 75,000 reservists have been called up.
A Tunisian delegation visiting Gaza Saturday reiterated the North African country's "unconditional solidarity" with the Palestinians.