The Soviet invasion of Afghanistan and Moscow's sharp verbal attacks on the NATO alliance have raised a serious challenge to the special relationship West Germany has elaborately constructed with the Soviet Union over the last decade.

Nevertheless, Bonn has been considerably more reluctant than Washington to signal the end of detente and the beginning of a new cold war. Although West Germany has condemned the Soviet incursion with strong language, it stopped short of announcing a review of its relationship with the Soviets.

The fresh display of Soviet belligerance -- coupled with Kremlin attacks on Bonn for its role in the recent NATO decision to place nuclear missiles in Europe -- poses an especially trying dilemma for the West Germans and their ostpolitik, or policy of rapprochment with Eastern Europe. It also places tremendous pressure on Chancellor Helmut Schmidt in an election year.

As a result, the Bonn government has been disinclined to undertake anything that might jeopardize its new relations with the East, a development that would threaten the aspirations of thousands of East Europeans seeking to emigrate to the West and of those West Germans who still have hopes of seeing a reunited German state.

Schmidt's ruling Social Democratic Party is the principal architect of the policy of better relations with the Soviets -- something many West Germans have come to believe in.

Moreover, the current crisis in East-West relations comes just a few months before Schmidt had planned to meet with both Soviet Communist Party chief Leonid Brezhnev in Moscow and his East German counterpart Erich Honecker. No firm date had been set for either meeting before the new deterioration in relations.

This fall Schmidt faces a tough opponent in Franz Josef Strauss of the conservative opposition. Strauss has always been more willing to talk tough to the Soviets than Schmidt has, and in the past week he criticized the Bonn government for reacting with little more than expressions of concern to the Soviet action in Afghanistan. He also recalled how he often has warned against being too soft on the Soviets.

Even so, Schmid't government appears to be concerned about possible American overreaction to the Soviet moves in Afghanistan, something observers here attribute at least in part to Bonn's uneasiness with U.S. national security adviser Zbigniew Brzezinski. West Germany's concerns appear to be shared with France.

Observers here say both countries doubt that NATO can exert more than limited influence in South Asia and would prefer to leave the problem to the United Nations, while concentrating their own energies on strengthening diplomatic and economic ties to the Middle East, Third World and so-called nonaligned nations.

In this connection, West German Economic Minister Otto Graf Lambsdorff left on a three-nation Middle East tour. Bonn has stepped up its diplomatic effort in Iran, using the development in Afghanistan to stress to Tehran that its real worry ought to be the Soviets and not the Americans. t

Sources close to the West German government said Bonn has told the revolutionary government of Ayatollah Ruhollah Khomeini that it would provide aid on the condition that the hostages at the U.S. Embassy in Tehran are released.

In any case, the West German sources say the Bonn government wants to avoid taking the lead in the NATO alliance so as not to strain its own relations with Moscow, although there is little doubt that the West Germans would stand firm in any common stand taken by NATO, as it has in the past.

Bonn showed tis sensitivity to the notion that it is in the forefront of NATO efforts by denying press reports that its NATO ambassador, Rolf Pauls, proposed a boycott of the 1980 Moscow Olympics during an emergency meeting on New Year's Day to discuss events in Afghanistan.

Meanwhile, other NATO allies are less reluctant to take the lead. British Foreign Secretary Lord Carrington has announced a fact-finding tour of the Middle East and characterized Soviet explanations of the Afghan invasion as "childish."

Nevertheless, Washington Post correspondent Leonard Downie Jr. reported from London, the British are more interested in a coordinated NATO or Common Market response to Moscow because of the dramatic impact such collective action would have.

Downie said sources indicated that the British are seeking a dramatic gesture of collective disapproval, such as the coordinated withdrawal of all NATO or Common Market ambassadors from Moscow.

In line with its more cautious approach, the Schmidt administration thus far has refused to get into a public discussion about the health of detente, saying it is too early to tell precisely what impact the push into Afghanistan will have.

One basic reason for such refusal is that the term "detente" means something quite different -- something much more personal and sensitive -- to West Germans than to Americans.

As a leading, but geographically and militarily highly vulnerable power on the border between East and West, West Germany has taken pains to cultivate its special relationship with Moscow. It has begun to normalize ties with East Germany, settled old quarrels with Poland and gone out of its way sometimes not to offend the Soviet Union publicly.

Now, suddenly, the fragile stability between Bonn and the Soviet Bloc appears in danger of breaking apart. The souring of Bonn-Moscow relations began with the decision by NATO in early December to station for the first time in Europe American nuclear missiles that could reach the Soviet Union, a move the Soviets said would destroy the basis of negotiations between East and West.

West Germany fully supported the alliance plan, and afterward, the Soviet press carried increasily bitter attacks on the decision, highlighting West Germany's role. Previously, the Kremlin had portrayed Bonn's approval as the result of U.S. pressure, but it began to charge that the modernization decision was in fact a reflection of West Germany's own military intentions.

Last week an article in the Communist Party daily Pravda launched an unparalleled attack on Schmidt.

The article charged with direct responsibility for the NATO decision, comparing it with former West German chancellor Konrad Adenauer's decision to rearm West Germany. Pravda also accused Schmidt of "zig-zagging" and double talk," a reference to what Moscow saw as Schmidt's reluctance to take responsibility for publicly proposing the nuclear modernization idea during a 1977 speech in London.

One thing that keeps the Bonn government hopeful of eventual easing of the crisis in relations is the belief that there is no real alternative to detente -- for the West and particularly for the East. Moscow and the Soviet Bloc countries cannot economically afford a new arms race, sources close to the government here say.