Nearly 5,000 people gathered near Cairo's Al-Azhar Mosque, chanting anti-Israel slogans and carrying banners that read "No to Israel" and "Hey Arab leaders, you should be united."
Hosni Mubarak, the Egyptian president, met Jordan's King Abdullah II nearby to discuss the situation.
They issued a joint statement demanding "an immediate halt on attacking civilians and vital infrastructure," saying such attacks breached international humanitarian conventions, and called for restraint on all sides.
Egypt and Jordan are the only countries in the region to have signed peace treaties with Israel.
In Amman, more than 2,000 demonstrators gathered at a mosque after Friday prayers, shouting "Zionists get out, get out!" and "Lebanon, Palestine and Jordan are one people!"
Abdul-Hadi Majali, the speaker of Jordan's lower house of parliament, called on the international community to oppose Israel's actions, calling them a "flagrant defiance" of international law, the official Petra news agency reported.
Thousands of Iraqis demonstrated in Baghdad praising Hezbollah's leader and denouncing Israel and the US over the attacks. Some protesters said they were ready to fight the Israelis.
Nouri al-Maliki, the Iraqi president condemned the attacks and warned that they could lead to "an escalation of violence in the region." The influential Sunni Association of Muslim Scholars issued a statement urging the international community not to be silent.
Protesters in Kuwait criticised
Israel and the United States
In Kuwait, hundreds rallied in front of the seaside parliament, shouting "Death to Israel!" and "Death to America!" Some waved posters of Sheik Hassan Nasrallah, the Hezbollah leader, whose headquarters were bombed on Friday by Israeli planes.
"Arab countries can do nothing but condemn," Kuwaiti lawmaker Musallam al-Barrak said.
In Gaza, thousands of protesters marched at a Hamas-organised rally waving Palestinian and Lebanese flags.
"We in Hamas came here to tell our people in Lebanon that your blood is our blood, your enemy is ours and your aim is ours," one demonstrator shouted through loudspeakers.
Omar al-Bashir, the Sudanese president, said his country stands with the "Palestinian mujahedeen" and "backs the steadfastness of the Lebanese resistance," Sudan's official news agency reported.
Amr Moussa, the Arab League secretary-general, issued a statement calling on Israel to halt its military operations, and asking the UN security council to intervene. He met UN officials in Cairo ahead of an emergency summit of Arab foreign ministers on Saturday.