The Christian leaders of the holy city are following "with concern" reports the United States might unilaterally recognise the city as the capital of Israel.
"We have been following, with concern, the reports about the possibility of changing how the United States understands and deals with the status of Jerusalem", a letter from them Wednesday said, according to the Times of Israel.
"The Muslim Council of Elders stresses that this decision is illegitimate and completely unacceptable, that it is against all the laws and worldwide conventions which stipulate that Jerusalem is an integral part of the whole occupied territories of Palestine".
There is real concern not just for the preservation of the holy sites in Jerusalem - which holds special religious significance for Jews, Christians and Muslims - but also for the people who visit them, the priest said.
The statement emphasized that the decision would not change the Palestinian people's rights over Jerusalem and other occupied territories, and imposing a new status on Jerusalem was not possible.
"No one has the right to justify the [Israeli] occupation", of Palestinian land, including East Jerusalem, he said in a statement.
However, rather than doing this, the Trump administration's announcement "is very clearly putting Jerusalem right in the middle", the priest said, adding that there is also confusion over what this will mean in the long run.
The decision, AP said, will further negatively impact on relations between Israel and Palestine and the worldwide community's attempts to bring a resolution to the crisis.
Many Israelis, he said, are asking themselves the question: "is Israel going to have to pay a price for this American gift? We are certain that such steps will yield increased hatred, conflict, violence and suffering in Jerusalem and the Holy Land, moving us farther from the goal of unity and deeper toward destructive division".
"Our solemn advice and plea is for the United States to continue recognizing the present worldwide status of Jerusalem", the churchmen said.
Lebanon's Prime Minister Saad Hariri and Ministry of Foreign Affairs also denounced Trump's move on Jerusalem.
"Recognition of Jerusalem as the capital of Israel is not a recognition of the reality on the ground; it is an expression of support for Israeli policies, much of which is in contravention of the global law". Any sudden changes would cause irreparable harm.
In Iraq, Prime Minister Haider al-Abadi, a close USA partner in the fight against the Islamic State, called on Trump to reverse the decision, warning that it could further destabilize the region.
Elsewhere, militants who have fought USA troops took the opportunity to condemn both Israel and the United States.