Senior U.S. officials said Trump is due on Wednesday to recognise Jerusalem as Israel's capital and set in motion the relocation of the U.S. Embassy to the ancient city.
Pope Francis said he could not "keep silent about my deep concern" for Jerusalem and urged respect for "the status quo of the city in accordance with the relevant resolutions of the United Nations".
Pope Francis joined a chorus of negative reactions to Trump's decision to recognize Jerusalem as the capital of the Jewish state and move its embassy there.
The Pontiff made the remark ahead of an official announcement on Jerusalem by U.S. President Donald Trump.
Pope Francis has stated his "concern" over United States president Donald Trump's expected decision to recognise Jerusalem as the capital of Israel.
"Jerusalem is a unique city, sacred for Jews, Christians and Muslims", he said, adding that it was home to sites deemed holy by followers of the three major monotheistic faiths.
The former Holy See ambassador, who now serves as advisor to the Vatican's office for Integral Human Development, endorsed the appeal made by Pope Francis earlier on Wednesday to maintain the Status Quo of Jerusalem.More news: Ravens CB Smith suspended 4 games for PED violation
Arab leaders have warned the Trump administration's decision would subvert decades of US foreign policy and risk triggering further conflicts and violence in the Middle East.
The status of the city remains disputed. The Vatican said the call with Francis was made at Abbas' initiative. He will, however, direct the State Department to begin the process of moving the embassy.
In his comments to the group, Francis expressed his hope for "peace and prosperity" for the Palestinian people and called for dialogue that respects the rights of everyone in the Holy Land.
Dialogue, the pope said, takes place at every level, especially "in our families, in our religious communities, between different religious communities, and also in civil society".
"At the end of his weekly general audience, attended by thousands of people, the Pope called for the status quo on Jerusalem to be preserved, saying that he was very anxious because the American decision could "[add] new elements of tension to a global panorama" that is already marred "by so many and cruel conflicts".
However, a key condition for dialogue is mutual respect and a commitment to strengthen that respect "for the sake of recognizing the rights of all people, wherever they happen to be", he said.