President Carter cracked down hard on Maj. Gen. John K. Singlaub largely to remove any doubts in the minds of South Korean leaders that American ground troops were going home, administration officials said yesterday.

The Carter administration was in the midst of making the case to South Korean leaders for an American withdrawal when Singlaub said in an interview with The Washington Post that the step "will lead to war."

If that statement had been allowed to stand unchallenged by the President, administration officials contended, it might have been interpreted in Seoul as a sue sign that Carter's withdrawal plan was negotiable.

Before Singlaub spoke out in a story published May 19, Carter and Defense Secretary Harold Brown had agreed that South Korea had so many well-trained ground troops it would be safe to withdraw the 33,500 U.S. Army troops there between now and 1982.

Gen. Bernard W. Rogers, Army chief of staff, flew to Korea last month to explain Carter's decision to top American Army officers in Seoul, including Singlaub. Singlaub had been chief of staff, third ranking post in the command since last July.

Many U.S. military officers contend the South Vietnamese army would have developed better if its leaders had been convinced early that the Americans were going to leave the ground war to them. Carter did not want to leave any doubts on that score in Korea, officials said, and thus reacted strongly to Singlaub's dissent on withdrawal.

At the Pentagon, a spot check of officers indicated widespread agreement that Carter was justified in discipling Singlaub for criticizing out of military channels a national policy decision. But some officers said summoning Singlaub to the White House was overkill.

There was also sympathy among military people who have served in Korea for Singlaub's feeling that the toe-to-toe confrontation between North and Soutn would escalate to war at any sign of weakness, such as withdrawing troops. "But he should have handed in his suit if he wanted to challenged a presidential decision," said one general who counts himself among Singlaub's admirers.

Singlaub will be reassigned to one of the 182 billets the Army has for two-star generals. Gen. John W. Vessey, commander of United Nations and U.S. forces in South Korea, in a letter to Secretary Brown explaining the controversial interview, requested that Singlaub be kept in his current job.

One reason Carter declined to do that, officials said, was the feeling that Singlaub's position as the U.S. negotiator with the North Koreans at Panmunjom had been weakened by the flap. Vessey's letter, defense officials said, did not dispute the accuracy of the quotes attributed to Singlaub in The Washington Post story.

Singlaub, who will be 56 in July, is scheduled to retire from the Army no later than September, 1979, when he will have served the maximum five years in the permanent rank of major general.

Army officials said last night that Singlaub will be given a meaningful assignment. They predicted the two-star general will complete his Army career rather than retire ahead of time to go more public on his concerns.

Singlaub is scheduled to express his concerns about Carter's withdrawal plan Wednesday before the House Armed Services Investigations Subcommittee.

Said subcommittee Chairman Samuel S. Stratton (D-N.Y.) in announcing the public hearing: "The subcommittee will not address itself to the question of whether Gen. Singlaub should or should not have spoken out publicly as he did, or whether the President should or should not have removed him from command."

Rather, said Stratton, the subcommittee wants to find out why Singlaub believes removing American troops from Korea "would run a very grave risk of war . . ."