The Palestinian Medical Relief Society (PMRS) called on international leaders to demand that Israel is held accountable for the killing of dozens of Palestinian protesters in Gaza on Monday in what the organisation called a "horrible massacre."
In an official statement on Tuesday, the PMRS condemned in strongest terms the ongoing Israeli assault on civilians protesting along the Gaza border against the US embassy opening in Jerusalem.
The organisation called on its partners to demand that Israel immediately halt its unlawful use of force.
Israeli forces on Monday killed at least 61 people and injured at least 2,400 others in the bloodiest day in the Israeli-Palestinian conflict since the 2014 Gaza war.
"Nobody should remain silent while this horrible massacre continues against peaceful civilians," the PMRS said.
Monday's protests were aimed against the opening of the controversial US embassy to Israel in Jerusalem, which had angered Palestinians who want the eastern part of the city as their capital.
Tens of thousands of Palestinians rallied near the border fence, with smaller numbers seeking to breach it.
The grassroots community-based Palestinian health organization said in its statement that since the onset of the protests at the end of March, Israel has repeatedly violated all basic principles of international law regarding the use of force against civilians and has blatantly ignored international and internal calls to end the use of live ammunition against unarmed protesters.
It accused the Israeli officials of publicly standing by the decision to kill civilians who participated in peaceful protests.
Strong suspicion has been raised by human rights organizations, including Amnesty International, that orders were given to soldiers to shoot to maim.
"Children, disabled persons, journalists, first aid responders and medical personnel have been indiscriminately targeted and killed in complete violations of humanitarian law and any basic sense of humanity," the PMRS statement said.