Ronald Reagan's victory was greeted yesterday with a chorus of formal congratulations abroad that obscured widespread unease about America's dramatic shift to the right and its likely impact on the international climate.

Initial Soviet reaction involved an olive branch to Reagan in the form of assertion that Moscow is prepared to work with any U.S. president. But Reagan's election pledge to scrap the U.S.-Soviet strategic arms limitation treaty and insistence on U.S. military superiority were seen by the Soviets as threatening the existing basis of bilateral relations. [Details on Page A34.]

Western European diplomats judged Reagan's victory as likely to make American foreign policy more assertive, self-confident and consistent. But they were concerned about potential conflicts within NATO over Reagan's attitude toward the Soviet Union, detente, arms control and defense spending.

In a Gallic sneer at Reagan's past as an actor, the Paris newspaper France-Soir splashed under the front page headline "America Has Chosen" a picture of a gun-toting Reagan from a 25-year-old western movie that was aired on television election night.

Is Israel, informed officials said a Reagan administration could bring a significant shift in the Middle East peace process started by President Carter at Camp David two years ago. These officials do not expect any substantive Israeli-Egyptian talks until next spring. [Details on Page A36.]

Egyptian President Anwar Sadat, who praised Carter's "sincere, honest and relentless efforts" to get Israel and Egypt to open peace negotiations, expressed confidence in his message to Reagan that the United States would continue to press for peace in the Middle East.

Japanese government officials publicly doubted that a change of administrations in Washington would seriously affect bilateral relations. There was, however, an undercurrent of apprehension that a Reagan administration would press Japan harder than Carter did to increase its defense spending to become a stronger ally.

While withholding public comment, officials in Peking restated earlier warnings that any changes in Washington's China policy would lead to a worsening in Sino-American relations.

British Foreign Secretary Lord Carrington said he believed that Reagan "will be a realistic influence" on the NATO alliance and the world scene. Referring to Reagan's insistence on a strong military, Carrington said, "I don't think it is agressive, I think it is defensive."

It is Reagan's foreign policy team rather than his campaign rhetoric that is seen by European diplomats and analysts as the key to relations between his administration and the allies. According to several sources, the favored European candidate to become secretary of state is former treasury secretary George Shultz.

Sources in Paris said Shultz made private visits there in June and October and met at least once with French President Valery Giscard d'Estaing. The French president's congratulations to Reagan yesterday were described by French officials as unusually warm.

British analysts noted how closely Regan's policies -- especially his tough attitude toward Moscow and staunch free market economic philosophy -- resemble those of Prime Minister Margaret Thatcher. The two are likely to disagree, however, over SALT II, which Thatcher believes should be ratified.

Western officials said yesterday that Reagan's victory has placed the current Soviet-American arms control talks at Geneva in a state of suspended animation with both sides expected to mark time for months to come. Two sets of talks are currently under way there, one dealing with the issue of nuclear test ban, the other with eventual curbs on nuclear arms in EUROPE. A U.S. official said that Reagan was expected to order a serious review of the entire arms control process.

The public reaction of smaller European countries to Reagan's victory included point references to their concern about his foreign policy views. "Defense and detente are equally vital for us all," said Danish Prime Minister Anker Jorgensen in his congratulatory cable to Reagan. A Dutch spokesman said that "we are confident that Reagan's policies will lead to the maintenance of world peace, detente and the promotion of human rights."

A West German government spokesman in Bonn rejected speculation that Chancellor Helmut Schmidt was worried about Reagan's victory. But diplomats in several European capitals predicted friction between a Reagan administration and several NATO allies including West Germany over their strong commitment to nuclear arms control and their overriding desire to maintain East-West detente.

Schmidt, who is scheduled to visit Washington two weeks from now, was expected to be the first European leader to meet with Reagan. Some French analysts speculated that France, Britain and West Germany may coordinate their policies more closely to counter what is expected to be a strong pressure to follow Reagan's lead in the alliance.

Reaction in the rest of the world ranged from jubiliation among rightists in Guatemala and El Salvador to dismay in black Africa to cautious voices in the Phillippines, Mexico and Panama.

India's Prime Minister Indira Gandhi, while saying it "makes no difference who won the U.S. election," said in a message to Reagan that she hopes he would show understanding for country's problems. Indian journalists, however, expressed the view that Reagan's victory will be "bad for India and the rest of the developing world on bilateral trade, multilateral trade and aid." Moreover, Indians pointed out yesterday that Republican administrations generally favor Pakistan.

Several African observers expressed the view that a Reagan administration would switch its interest away from the Third World and Africa in particular. A key advisor to Zambia's President Kenneth Kaunda saw the change as setting back the "liberation of southern Africa for a whole generation." He said he feared that Reagan would remove even the limited pressure Carter had put on South Africa to grant independence to Namibia and dismantle South Africa's system of racial discrimination.

Some African diplomats voiced fears that Reagan would reduce U.S. aid to the continent and that he may be inclined to support anticommunist forces regardless of African concerns.

South African Prime Minister Pieter W. Botha, in his message to Reagan, raised the issue of "communist influence" in southern Africa and obliquely referred to the arms boycott against South Africa. Botha said he expected a "period of reasonable consultations" in reference to South African hopes that a Reagan administration would abandon the verbal pressure of the past four years.

While South Korea and Taiwan welcomed Reagan's landslide, Iran said the election would bring no change to the hostage situation, Cuba assailed the prospective change in Washington as a return to a gunboat diplomacy and the Palestine Liberation Organization described it as a victory for Israel.