Some thousand demonstrators on Sunday gathered in Manhattan in solidarity with Palestinians as pro-Israel marchers counter-protested following a bloody escalation in the Middle East conflict.

The rallies followed Saturday's surge in violence that's killed hundreds and wounded thousands in the region after militant group Hamas launched a deadly assault on Israel which responded by hammering blockaded Palestinian Gaza with heavy air strikes.

Demonstrators in New York waved Palestinian flags during the peaceful march from Times Square to near both the Israeli consulate and the United Nations headquarters, where the Security Council was to convene over the weekend's violence.

"We are here in solidarity with the Palestinian people who are fighting 75 years of Israeli settler colonialism, settler violence, and 16 years of military blockade of Gaza," said Munir Atalla, a 30-year-old member of the Palestinian Youth Movement group, which was among the demonstration's organizers.

"What we saw yesterday was the people of Gaza breaking out of their open-air prison," he continued.

"It's impossible to view the events of this week, without first understanding the context that the Israeli regime is founded on violence… it's founded on the erasure and annihilation of Palestinians."

Counter-demonstration

The rally was among others backing the Palestinian cause in American cities including Washington and Chicago.

The demonstrations came as the United States quickly affirmed its support for Israel, with US President Joe Biden ordering US ships and warplanes closer to its ally and sending fresh military aid.

"Not another nickel, not another dime, no more money for Israel's crimes," protestors in New York chanted.

Sarah Barqawi, 38, told AFP she came to Sunday's rally "because my family is currently under siege in Gaza and are just waiting to know if they will be alive or dead, without any electricity, without any support, without any supplies."