President Reagan plans to offer U.N. Ambassador Jeane J. Kirkpatrick the post of administrator of the Agency for International Development and will emphasize his personal desire to keep her as a policy adviser, well-placed administration sources said yesterday.

While these sources were optimistic that Kirkpatrick would accept the offer, sources close to the U.N. ambassador said it was unlikely that she would.

They acknowledged, however, that Kirkpatrick is under heavy pressure from conservatives in and outside the administration to accept any post Reagan might offer that would keep her close to the foreign policy decision-making process. Reagan said yesterday in an interview with Helen Thomas of United Press International that he intends to offer Kirkpatrick a high-level foreign policy position, but he would not specify one.

"It is a department of the executive branch that I'm not free to talk about yet that I think she would be very good at," the president said.

Administration officials said Reagan will meet with Kirkpatrick at the White House next Wednesday to discuss her future. They last met on Dec. 10 and later announced that they would get together again after the president's inauguration.

Asked about the report that Reagan will offer her the AID post, Kirkpatrick said yesterday through a spokesman: "As I said after my Dec. 10 meeting with the president, I will have no further comment about my future until we meet again."

There was no comment either from AID Administrator M. Peter McPherson, who has not given any indication that he is leaving the administration.

The sources close to Kirkpatrick observed that in October 1983 she had turned down the AID job, one of three positions that Reagan reportedly offered her after administration moderates blocked her from succeeding William P. Clark as Reagan's national security affairs adviser.

The White House political lineup has changed markedly since then.

White House chief of staff James A. Baker III, considered a Kirkpatrick opponent, has been nominated as secretary of the treasury. White House counselor Edwin Meese III, a Kirkpatrick supporter, has been nominated as attorney general.

Robert C. McFarlane, who succeeded Clark as national security affairs adviser, has stayed on and gradually become a power in the White House. When reports surfaced after the Nov. 6 election that McFarlane might leave, Reagan made it known that he did not want to replace either his national security adviser or Secretary of State George P. Shultz.

The sources close to Kirkpatrick acknowledged that Reagan might be able to change the ambassador's mind about the AID post if he is particularly persuasive when they meet. But they stressed that she considers the AID post essentially a second-echelon job that has a limited scope and and does not offer the chance to participate in major foreign policy decisions.

According to the sources, Kirkpatrick believes that after four years in the highly visible U.N. post, she cannot accept any job that is regarded as less important without creating an impression that she has been demoted or sidetracked. In her view, that would erode her influence.

But conservatives in the administration have a different view.

They point out that Reagan prides himself on taking advice from Cabinet officers and other officials beyond the range of their official responsibilities. They also say Kirkpatrick would strengthen the conservative voice in the administration.

The question of whether she could perform this function more effectively in or out of government is likely to determine her decision, these officials believe. Administration officials said she is more likely to be given a top foreign policy post if she takes Reagan's offer next week.

In the past four years, Kirkpatrick has forged a reputation as an exceptionally bright and tough-minded advocate who has won Reagan's respect for her opinions and her performance at the United Nations.

However, she also is regarded as abrasive by many administration officials. Neither Shultz nor McFarlane was said to care for the idea of letting her succeed Meese as White House counselor, but White House officials said yesterday that McFarlane would welcome her as administrator of AID.