The OIC convened in Jeddah on Monday to discuss the plan Trump unveiled alongside Israeli prime minister Benjamin Netanyahu at the White House on Tuesday.
The 57-member organization said it "calls on all member states not to engage with this plan or to cooperate with the US administration in implementing it in any form".
The deal would, among other contentious things, enshrine Jerusalem al-Quds as “Israel’s undivided capital” and allow the regime to annex settlements in the occupied West Bank and the Jordan Valley.
All Palestinian groups have angrily rejected the plan, while Israeli groups of different political persuasions have enthusiastically embraced it, hailing it for offering them more than they expected.
Palestinian Authority leader Mahmoud Abbas on Saturday cut relations with the US and Israel after saying he did not want his name to go down in history for betraying the Palestinians.
Riyadh, however, has welcomed the initiative, saying "the Kingdom appreciates the efforts made by President Trump’s administration to develop a comprehensive Palestinian-Israeli peace plan".
Saudi government media on Sunday urged the Palestinians not to miss "this opportunity" and to approach the deal with a positive mindset.
State-run newspaper Okaz went on as far as to say that “the Palestinian cause is no longer the Arabs’ main cause”.
Saudi Arabia meanwhile barred an Iranian delegation from the OIC meeting in Jeddah, Iran's Foreign Ministry spokesman Abbas Mousavi said.
Iran, he said, has filed a complaint with the OIC and chastised Saudi Arabia for misusing its position as the host for the organization's headquarters.
Iranian officials have condemned Trump's plan as a non-starter after it was officially announced last week. The Palestinian leadership has rejected the plan, saying it heavily favors Israel and will deny them a viable independent state.
Iran: Trump deal amounts to sellout of Palestine
Iran's Foreign Ministry spokesman says US President Donald Trump’s initiative for resolution of the Palestinian-Israeli conflict seeks to fully compromise the Palestinian cause.
Abbas Mousavi called the scheme “one of the most disgraceful of proposals and initiatives,” saying the US has devised the plan on the basis of ignorance of the Palestinian nation’s rights.
“From the Iranian people’s perspective, the ‘deal of century’ amounts to an imposed peace and the selling of Palestine,” he added.
“This plan is consigning the Palestinian cause to oblivion,” Mousavi said, adding that the Islamic Republic’s government will stand by the Palestinian government and people until the liberation of the holy occupied city of Jerusalem al-Quds.
Trump had announced the scheme, which he has controversially named the “deal of the century,” years ago but withheld its details.
Palestinian demonstrators take part in a protest against a US-brokered so-called Middle East peace plan, while holding placard that reads in Arabic " down with the deal of the century, down with [US President] Donald Trump and [Israeli Prime Minister] Benjamin Netanyahu," in Rafah in the southern Gaza Strip, on February 1, 2020. (Photo by AFP)
On Tuesday, he unveiled the scheme’s outlines, which features the recognition of al-Quds as Israel’s “capital” -- although Palestinians want the city’s eastern part as the capital of their future state.
Trump also said under the plan, Israel would be annexing the settlements that it has been building in the West Bank since occupying the Palestinian territory in 1967.
This is while all previous foreign-mediated agreements between the Palestinians and Israelis as well as repeated United Nations resolutions have mandated Tel Aviv to withdraw behind the 1967 borders.
Palestinians, who had already spurned the plot, repeated their opposition to it soon after Trump’s announcement.
Mousavi said the only way out of the 70-year-old impasse brought about by Israel’s declaration of existence in 1948 is to seek recourse to popular vote concerning the fate of Palestine.
He also regretted some Muslim states’ alignment with Washington and Tel Aviv on the Palestinian issue.
“They do not discern their enemies from their friends,” the spokesman said. He hoped that recent developments help them rectify their views “and realize that their enemy is not but the entity called Israel.”