Secretary of State Cyrus R. Vance, outlining a "forward-looking and positive" policy toward Africa which deemphasizes East-West confrontations there, yesterday announced U.S. willingness to begin working with Marxist Angola "in more normal ways."

In a restatement of U.S. policy - which has been the subject of intense speculation inside and outside the Carter administration in recent weeks - Vance stopped short of offering full diplomatic relations to the Angolans. Aides said that step is unlikely before the withdrawal of at least some of the 20,000 Cuban troops estimated to be on duty there, but in the meantime, a visit to Angola by a policy-level U.S. official is planned.

Vance justified the cultivation of better relations with Angola by citing the need for that country and its neighbor, Zaire, to reach agreement "to respect their common border and not to interfere in each other's internal affairs."

Informed sources said the United States has undertaken a diplomatic campaign for an Angola-Zaire pact to prevent cross-border raids in either direction. Such an agreement would prevent recurrence of the periodic attacks by Angola-based exile troops on Zaire's mineral-rich Shaba Province as well as raids by Zaire-backed forces into Angola.

In his speech to the annual gathering of U.S. Jaycees meeting at Atlantic City, Vance did not repeat the Carter administration's charge that Cuba played a key role in training and equipping the forces that invaded Shaba, and that Angola shared the responsibility.

While expressing concern in general terms about Soviet and Cuban activities in Africa, Vance said "an affirmative approach to African aspirations and problems" is the most effective U.S. response. "Any other strategy would weaken Africa by dividing it. And it would weaken us by letting others set our policies for us." he said.

As in his lengthy presentation Monday to the House International Relations Committee, the Vance address was far less combative and far more cautious about East-West rivalry than some recent statements of President Carter and his White House national security adviser, Zbigniew Brzezinski.

State Department officials said yesterday's speech had been read an approved in advance by Brzezinski in a late stage of its development and that Brzezinski's deputy, David Aaron, had had a hand in earlier stages of drafting.

It was unclear to what extent Vance's appearances in the past two days represent a shift in policy by the Carter administration on Soviet and African affairs. There is no doubt that they represent an effort to cool the heated rhetoric in the face of across-the-board protests and public warnings from the Soviets and openly expressed misgivings on Capitol Hill.

There has been no new National Security Council meeting in the past few days to consider new lines of approach to foreign policy, officials said. White House officials continued to refer to Carter's June 7 Annapolis speech as the definitive statement of U.S. policy. In it he challenged Soviet leaders to choose "confrontation or cooperation."

One White House official described Vance's declarations as "elaborations" of the Carter stand and said the secretary of state was being "supercautious" because stronger statements have been "puffed way up" to suggest policy shifts.

A State Department official said that, on Africa at least, the shift in rhetoric had been much greater than the eexplicit shift in policy. Vances recent appearances returned the rhetoric to the relatively uncontroversial level that obtained before the alarm over Cuban involvement in Shaba, the dispatch of U.S. military transports to Zaire and a link between Africa and the strategic arms limitation talks (SALT) suggested to many that a broad-scale policy reversal was under way.

Officials conceded that new African espisodes or strong new statements from Carter or Brzezinski could raise questions about policy once again.

In an effort to put down speculation and display a united front, Carter, Vance, Brzezinski and Defense Secretary Harold Brown were scheduled to participate together in a White House briefing for about 80 members of Congress last night.

Whether termed rhetoric or policy, the Vance speech on Africa reflected substantial change in the U.S. stand toward Angola and Zaire.

Despite some quiet diplomatic contacts at the United Nations and elsewhere, there had been little but open condemnation in recent administration pronouncements about Angola. On the other hand, there was much verbal support for Zaire and the physical support of the U.S. transport and material aid.

Vance's bid for better relations with Angola was described by officials as arising from private indications from the Angolan government of a desire to discuss a variety of questions with United States, including the border with Zaire and the situation in South Africa-ruled Namibia to the south, where the U.S. is seeking a negotiated transition to independence.

Concerning Zaire, Vance expressed U.S. willingness to provide economic and military assistance, but said that this "must be accompanied by a genuine effort on Zaire's part to solve its long-term problems."

Vance then spelled out a series of major requirements which, in more explicit terms, are reported to have been presented to Zaire's President Mobutu Sese Seko as conditions for additional help.

In Vance's language they are "internal economic reforms," "strengthening the management and organization of its armed forces" and "broader participation in the political life of Zaire."

A Zairian effort to reach a border pact with Angola, mentioned the next paragraph of Vance's speech, may be another requirement for U.S. assistance.

Reports from Zaire said Mobutu was presented with separate letters Monday and Tuesday by the ambassadors of the United States, Belgium, France, West Germany and Britain, outlining their conditions for new emergency aid to the debt-ridden country.

Vance's speech reiterated the U.S. commitment to seek negotiated solutions to the black-white conflicts of southern Africa, saying that "the great question is whether peace or violence will be the instrument of change."

Vance said the United States continues to hope that the Ian Smith regime, including his associated black leaders in Rhodesia, can be brought together with the guerrilla forces on the outside, and that a negotiated settlement can be obtained in Namibia.

While saying that the United States has no wish to see whites driven from South Africa and does not seek to impose a timetable or blueprint, Vance repeated that "a failure to begin to make genuine progress" toward an end to apartheid and full political participation for all will have "an increasingly adverse impact" on U.S. relations.