At the same time, Morsi appears to be trying to turn the crisis to his advantage by depicting Egypt as the Arab world's main protector of the Palestinians after years under Mubarak, who was closely tied to Israel and opposed to the Hamas militant group.
"Egyptians love peace . . . but they have always been able to fend off aggressors and protect the land, the nation and the Muslim world," he said in his address at a mosque near his home in a Cairo suburb. "We are even more insistent on remaining a protective shield to the Arab and Muslim world."
"We say to the aggressor, peace will never be achieved through aggression . . . because war does not build stability or peace," Morsi said. "This blood will be a curse on you," he said as the crowd in the mosque chanted, "God is great" and "With our blood and souls, we sacrifice for Palestine."
"I say to the aggressor to take a lesson from history and stop this farce and bloodshed or else you will face the wrath of the people and their leadership," he said. "Egypt today is different than Egypt yesterday and that the Arabs today are different than the Arabs of yesterday."
Morsi has pulled Egypt's ambassador from Tel Aviv to protest Israel's bombardment of Gaza, which Israel says was launched in retaliation for rocket attacks by Islamic militants in Gaza.
The dispatching of his prime minister, Hesham Kandil, was a dramatic if largely symbolic show of support for Hamas, which is effectively the Palestinian branch of the Muslim Brotherhood. Kandil is the highest level Egyptian official to visit Gaza since Hamas took over the territory in 2007 after winning elections two years earlier.
Despite the strong rhetoric, Morsi's government continues to work closely with Israel on security issues pertaining to the Sinai Peninsula, where militants have launched attacks on Egyptian forces and Israel. Since his election, Morsi has promised to abide by Egypt's 1979 peace deal with Israel.
The Palestinian cause unites Egypt's feuding political factions, from secular leftists to conservative Islamists, and all are putting pressure on Morsi to be tough on Israel.