The denunciations coincided with angry rallies in Lebanon, Jordan, Libya, Yemen, Tunisia, Turkey, Morocco, Iran and the Israeli-occupied West Bank, with more planned on Wednesday following calls for a "day of rage" across the region.
Israel and Palestinian militants have traded blame for the hospital strike on Tuesday night, with the Israeli army saying on Wednesday it had "evidence" that militants were responsible.
But the United Arab Emirates and Bahrain, which both established ties with Israel in the Abraham Accords of 2020, condemned the "Israeli" attack which came as Israel lays siege to Gaza.
"The United Arab Emirates strongly condemns the Israeli attack... resulting in the death and injury of hundreds of people," the UAE's official WAM news agency said early on Wednesday.
Bahrain's foreign ministry "expressed the Kingdom of Bahrain's condemnation and strong denunciation of the Israeli bombing," the Bahrain News Agency said.
Morocco, another country that recognised Israel in 2020, also blamed it for the strike, as did Egypt, which became the first Arab country to normalise relations in 1979.
Egyptian President Abdel Fattah al-Sisi condemned in the strongest terms "the Israeli bombing" of the Ahli Arab hospital, which led to "the deaths of hundreds of innocent victims" among the Palestinian citizens in Gaza.
He called the "deliberate bombing" a "clear violation of international law."
Saudi Arabia, which has ended talks on potential ties with Israel since violence flared, called the blast a "heinous crime committed by the Israeli occupation forces."
- 'War crime' -
During a press conference in Beirut on Wednesday, Palestinian Islamist group Hamas called for attacks against Israeli forces in the West Bank and other territories in response to the hospital strike.
"We call on our people in the West Bank and our people in Palestine...to rise up against the Zionist enemy and clash with its forces in all cities, villages and camps," Hamas official Osama Hamdan told reporters.
Hamdan called for region-wide protests on Friday and Saturday, demanding the "expulsion of the ambassadors of the Zionist entity in all Arab and Islamic capitals."
Jordan said Israel "bears responsibility for this grave incident" while Qatar, which has close ties to Hamas, slammed the "brutal massacre."
The Organisation of the Islamic Conference, also blaming Israel, called it "a war crime, a crime against humanity, and organised state terrorism."
Gulf Cooperation Council secretary general Jasem Mohamed Albudaiwi said it was "glaring evidence of the serious violations by the Israeli occupation forces."
Arab League chief Ahmed Aboul Gheit called on Tuesday for leaders to "stop this tragedy immediately."
"What diabolical mind intentionally bombards a hospital and its defenceless inhabitants?" he wrote on X, previously Twitter.
The strike came during a wave of deadly Israeli air strikes on Gaza following an attack by the Palestinian militant group Hamas that killed 1,400 people.
Lebanon's Iran-backed Hezbollah movement called for a "day of rage" against Israel following the attack as hundreds rallied at the US and French embassies overnight, where they scuffled with security forces.
More protests are planned for Wednesday, with Lebanon joining other Arab states in declaring a day of national mourning.
In Tunisia, thousands gathered outside the French embassy demanding the expulsion of the French and US ambassadors in protest at their governments' support for Israel.
Iraq, which also blamed Israeli authorities, demanded an "immediate and urgent resolution" from the UN Security Council to stop Israel's Gaza onslaught, as hundreds protested in the capital Baghdad, brandishing Palestinian flags.
Algeria condemned the strike as a "barbaric act" carried out by "occupation forces."
Libya's Tripoli-based internationally recognised government called the hospital strike a "despicable crime" as several hundred people protested in Tripoli and other Libyan cities.
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