President Reagan yesterday asked Health and Human Services Secretary Margaret M. Heckler to take a "promotion" to become ambassador to Ireland, but Heckler asked for a few days to consider the move, White House spokesman Larry Speakes announced.

Heckler, under pressure from White House chief of staff Donald T. Regan to leave the Cabinet, met with the president privately for 50 minutes in the Oval Office and then left the West Wing without comment. Heckler did not confer first with Regan, as some officials had said earlier was desired by the chief of staff.

Although White House officials have pressured other Cabinet members to resign in the past, it was the first time Reagan has personally asked a department secretary to leave his Cabinet. It was particularly unusual because Reagan has often vigorously defended his political appointees against criticism. The request signaled the increasingly powerful role played by the chief of staff.

Speakes announced that Reagan had made the decision to ask Heckler to leave. However, other White House officials said they were aware of "talking points" prepared for the president earlier in the day by Regan or his subordinates. These points were nearly identical to the language used in the announcement of Reagan's request later in the afternoon.

Speakes said Reagan was prepared to accept Heckler's resignation from the department and announce her appointment yesterday, but she asked for the delay and "she remains as secretary of health and human services." Questioned as to what would happen if she rejects the offer, Speakes said, "I do not have an answer to that. The president believes that Secretary Heckler is well-qualified" to be ambassador to Ireland.

"She is, of course, an American of Irish descent who has served with distinction as a member of Congress and as a member of the president's Cabinet," he added.

"She would make a valuable contribution in U.S.-Irish relations and would be able to work toward solving problems in the region," Speakes said, describing the diplomatic post as being in "an important part of the world" and a "key country" that "we have valuable relations with."

"The president would consider this a promotion," Speakes said, to skeptical laughter from reporters. However, Heckler would have to take a pay cut from her current salary of $86,200 to about $70,000, a White House spokesman said.

An associate of Heckler said she was "genuinely undecided" about whether to accept the president's offer, adding that she would make up her mind "within a day or two."

Speakes said Reagan made no other offer to Heckler, apparently leaving her the choice of accepting it or leaving the administration.

Earlier yesterday, Reagan, appearing angry, told reporters at a picture-taking session, "There has never been any thought in my mind to fire Margaret Heckler. I don't know where these stories come from. They are not true." But he said that "does not mean I don't have something else that I would want her to do." He added later, "I want to talk to her about something I've had in mind for her."

But when asked if Regan or others had recommended he find another job for her, the president said, "No more comments."

Senate Majority Leader Robert J. Dole (R-Kan.) said he called Regan at Heckler's request last week. "I think she's done a good job," said Dole, whose wife, Transportation Secretary Elizabeth Hanford Dole, is the only other woman in the Cabinet. But he added, "I'm going to try to stay out of it."

Rep. Henry A. Waxman (D-Calif.), chairman of a House health subcommittee, told CBS News last night that "I have to believe this is an ideological problem, that she's not pure enough for the right-wingers."

Rep. Judd Gregg (R-N.H.) said "unelected" White House officials were behind the move and that Heckler "has been, according to them, unloyal or disloyal and for this she must be burned at the stake or at the minimum at least sent to Ireland."

Heckler, 54, said last month she did not want the post, which would mean a substantial downgrading from her current responsibilities for administering the major federal health and welfare programs, as well as Social Security.

"That's a lovely position -- for someone else," she said then. The post has been vacant for several months; White House officials have said it was being held open for Heckler. Although not a major diplomatic job, the Dublin post is symbolically important to Reagan, who is also of Irish descent.

Heckler was appointed to head the department in 1982, after she was defeated in a Massachussetts congressional race. She had served as a Republican House member from the state for 16 years.

Officials said Regan had criticized Heckler for poor management of the department, but his specific complaints are not known. The White House had held up some top appointments at the department and ignored Hecker's proposed candidates for them. Speakes said the White House was "looking for the right people."

White House officials have said they thought that Heckler was given plenty of advance warning about dissatisfaction with her performance and that she should have taken it as a signal to leave quietly. But officials close to Heckler said she did not view it this way and felt she was under unremitting criticism from the White House.