The United States will join France, Belgium, West Germany and perhaps other European allies in a Paris conference next week to explore joint Western-African action to counter Soviet-Cuban military activity in Africa, the State Department said yesterday.

American participation in any new defense-support role in Africa, spokesman Hodding Carter said, "will certainly not involve U.S. combat troops."

"I think what we did in (Zaire's) Shaba Province the last few weeks is some indication of the kind of approaches we would be willing to consider," the spokesman said.

Secretary of State Cyrus R. Vance said last night, however, that "the principal reason" for the Western allies' talks in Paris next week is the "economic" damage done to Shaba province by the recent intrusion of rebels from pro-Marxist Angola, and the general state of Zaire's economy rather than discussion of a possible pan-African defense force.

The security concept, Vance told a news conference at the State Department, "is an interesting idea," which he said "I would guess" may "come of U.S. up" in Paris. But Vance said "it is much too early to draw any conclusions on it."

Vance made it clear he wanted to roll back the attention focused on the possibility of U.S. participation in an African defense mechanism, which can be highly controversial. The Paris meeting next week, Vance said, should be regarded only as "a preliminary meeting" to prepare for a long-planned conference in Brussels June 13-14 for in-depth discussion "of the economic problems of Zaire."

Officials acknowledged last night that the Vance statements were intended to diminish the attention given by the State Department's spokesmen earlier, in response to questions at his noon briefing, about the African security concept.

The Washington Post reported yesterday that French Foreign Minister Louis de Guiringaud said the United States and France have agreed to help African nations to protect themselves against "destablizing external forces" in Africa, if the African nations "put together some operative arrangement."

That decision was reached at a White House dinner last Friday between President Carter and French President Valery Giscard d'Estaing. France and Belgium sent paratroops into Zaire to rescue Europeans caught in the fighting when forces based in Marxist Angola raided the copper center of Zaire's Shaba Province earlier this month.

Officially confirming the Carter administration's interest in supporting an African force to counter external intervention, the State Department spokesman said yesterday:

"An African force in Zaire, specifically in Shaba, is one of the possibilities which the government of Zaire, together with other African governments, as well as the governments of Belgium and France, have raised . . .

"We are prepared to assist in such an approach in a limited manner, in accordance with well-established, clearly defined guidelines, which would be developed in further consultation with representatives of interested governments."With respect to more general concern about the security and stability of Africa, raised by African states themselves - concern which has been brought to the fore again by the invasion of Shaba Province - we are [also] prepared to discuss this broader question with interested states . . ."

"There is no distinct plan," State Department spokesman Carter stressed. He said "no clear picture has emerged of possible international co-operation on this kind of question . . ."

carter said that "as a further caveat," he wanted to emphasize that "in any case, our participation will certainly not involve U.S. combat troops."

He then cited the example of U.S. action in porviding air and logistics support for the French and Belgian forces which parachuted into Shaba province.

When asked if the constraints on future U.S. action will permit the United States to send military advisers or other ground personnel to support an African defense force, the spokesman said it was too premature to be able to answer those questions.

"I am not aware of specific conversations about specific activity," he said.

The Carter administration's "basic concern, he said, continues to be that Africans should deal primarily with Africans problems.

Possible U.S. support now being explored, he said, should not be construed in any way as indicating that the Carter administration has decided "to make Africa a battleground for great power confrontation." Instead, he said, the United States feels compelled - "to deal with what, unfortunately, seems to be a reality" in Africa - referring to extensive Soviet-Cuban military involvement in Africa.