President Reagan tentatively plns to nominate as ambassador to Morocco a Chase Manhattan Bank official who was involved in a 1979 contoversy about whether David Rockefeller and Henry A. Kissinger pressured the Carter administration to admit the late Shah of Iran to the United States.

Administration sources said yesterday that the Rabat embassy post is expected to go to Joseph Reed, a Rockefeller aide and Chase Manhattan board member who has handled many of the bank's dealings with foreign governments and clients.

In that capacity, Reed is known to have been in charge of efforts by Rockefeller, Chase Manhattan's former chairman, to assist the late shah, Mohammad Reza Pahlavi, for years an important client of the bank, after he was forced into exile in 1978.

These efforts included helping the deposed shah find places of refuge and, according to fomer secretary of state Kissinger, pressuring the campaign to get the shah admitted for medical treatment in this country in October 1978, a move that helped provoke the seizure by Iranian militants of the U.S. Embassy in Tehran and the resulting 14-1/2 month Iranian hostage crisis.

Reed could not be reached for comment yesterday. However, Chase Manhattan spokesman Charles Francis said Reed "understands he is being considered for an ambassadorial post." Although Francis said it would be "inappropriate" to discuss specifics, he added, "If he is asked, Mr. Reed certainly would be honored to serve."

Shortly after the hostage crisis began Nov. 4, 1979, allegations were made that then-president Carter had been pressured by Kissinger and Rockefeller to give the shah medical sanctuary.

In a Nov. 29, 1979, article on the op-ed page of The Washington Post, Kissinger contended that he became involved in assisting the shah at the request of the Carter administration and that he, in turn, appealed for help to Rockefeller, who initially was reluctant to do anything that might jeopardize Chase Manhattan's relations with revolutionary authorities in Iran.

Kissinger added that he and Rockefeller did help the shah in relocating his residence from Moracco to the Bahamas and subsequently to Mexico, and with such matters as arranging schooling in the United States for his children. Kissinger said contacts with the U.S. government on these matters were handled by Reed.

Later, Kissinger said, after it became known the shah was suffering from cancer, Reed presented medical evidence of his condition to David Newsom, then undersecretary of state for political affairs.

Kissinger wrote: "My understanding is that Joseph Reed presented the medical records to undersecretary Newsom, and on the basis of those records the administration admitted the shah for treatment."

Morocco is a pro-western monarchy whose ruler, King Hassan, has been engaged in overcoming domestic unrest. Despite concern of many observers about the stability of Hassan's rule, the United States had been moving to give him increased arms support for a campaign against Algerian-supported guerrillas in a disputed region of the Western Sahara.