The head of President-elect Ronald Reagan's State Department transition team has told Foreign Service officers to expect "a fundamental change of course" that will be "avowedly nationalistic" and that will avoid "the abstractions" -- such as undue emphasis on human rights -- that characterized President Carter's foreign policy.

In a private talk to some of the department's younger officers on Dec. 9, Robert E. Neumann defined "nationalistic" as "a belief that the basic criteria for American actions ought to be American national interests." While saying that such interests should not be selfish or narrowly focused, Neumann stressed that "when push comes to shove," U.S. relations with other countries should be guided primarily by what is best for American policy aims rather than, for example, a given country's human-rights record.

Second-hand accounts of Neumann's week-old remarks have circulated widely through Foreign Service ranks and touched off widespread concern that the incoming administration plans to accompany its policy shifts with a deep-reaching purge of State Department personnel judged to be unsympathetic or disloyal to Reagan's aims. Some versions of his remarks have left the impression that such a purge would penetrate beyond Carter's political appointees to middle-level career officers whose loyalty to Reagan becomes suspect.

However, notes made by persons present at the meeting do not bear out the rumors that Neumann, either directly or through implication, warned of a purge extending through the ranks. In fact, Neumann, who served as an ambassador to Afghanistan and Morocco in previous Republican administrations, went out of his way to stress his support of the career Foreign Service and to state that, unlike some people influential in the Nixon administration, he and his transition team colleagues do not believe the State Department is filled with "McGovernite Democrats."

He did say that the policy changes will be far more than cosmetic. That, he added, means that some officials identified with specific policies will be replaced by people in tune with the philosophy and goals of the new administration. But, Neumann noted, such shifts are normal in any change of administration, and he added that career officers displaced from jobs they hold now will have their rights protected and be given their opportunities commensurate with their rank and experience.

In an interview, Neumann, while defending this position, conceded that part of the transition team's mandate is "essentially negative" because it involves identifying those policymaking positions within the department where Reagan and his secretary of state-designate, Alexander M. Haig Jr., will want to consider personnel changes. Also, while it is an open secret that the transition team will be making recommendations about who should get certain policy jobs, Neumann stressed that personnel selection isn't the team's primary mission. "We don't nominate people, and our recommendations may not be accepted," he insisted.

"It is not clear at all who will get various posts," he continued. "There is a lot of lobbying going on by people who want jobs, and there are names circulating all over Washington about who will get what. But i can tell you that no decisions have been made, and these names are circulating without authority."

Although Neumann refused to go into detail, reliable sources said the principal difference of opinion within the transition team involves whether dealings with the Soviet Union and its East European satellites should be moved from the Bureau of European Affairs to a separate new office. Neumann and the majority of the transition team are understood to oppose the idea.

Also unclear is the status of the Bureau of Human Rights. Although Neumann said human rights will continue to be an element of U.S. policy, there is known to be strong sentiment within the transition team for giving the matter lesser priority by eliminating the bureau, now headed by an assistant secretary, and having a special assistant to the secretary of state deal with the subject.