Chancellor Helmut Kohl, in his first major policy address to parliament, declared today that West Germany is facing the worst economic crisis in its history and, reiterating austerity plans, summoned the nation to accept "a new economic policy and a new social policy."

Touching on a wide range of pressing domestic and foreign issues that his week-old coalition faces, the new Bonn leader also said West Germany would try for improved relations with the United States while hoping for "good relations" and more trade with the Soviet Bloc.

Commenting publicly for the first time on the banning of Poland's Solidarity union, the conservative Kohl condemned the move as a "cold surprise strike against the Polish people," but he gave no indication that West Germany would support additional sanctions against the Warsaw military regime.

The latest repression in Poland is proving an early test for the balanced East-West foreign policy that Kohl and West German Foreign Minister Hans-Dietrich Genscher intend to practice. The new chancellor today appeared to be as reluctant as his predecessor, Social Democrat Helmut Schmidt, to initiate tough measures in reponse to Polish government moves against Solidarity.

Senior aides in the chancellery and Foreign Ministry privately voiced doubt that West Germany and the other European allies will agree on new sanctions, arguing that there was little the West could do to help the Polish people and, as one aide put it, "not just do something for the sake of doing something."

"The federal government is following the developments in Poland with great sympathy and with great worry," said Kohl, whose center-right coalition of Christian Democrats and Free Democrats ousted Schmidt in a parliamentary vote Oct. 1.

Kohl repeated standing Western demands for the lifting of martial law in Poland, the freeing of all internees and the resumption of talks between the Roman Catholic church and the Warsaw regime. He also demanded reversal of the ban on Solidarity.

"The ban on the independent trade union Solidarity," said the chancellor, "is not only a breach of promises made by the Polish government, not only a violation of the Helsinki Final Act the 1975 accord reached by the Conference on Security and Cooperation in Europe , but also a cold surprise strike against the Polish people."

Kohl mentioned only one specific action that his government intends to take in response: to waive postal charges on Christmas packages to Poland.

Plainly adopting the pro-detente policy that was begun by Schmidt's center-left coalition, Kohl said he would carry on an "active peace policy" towards Eastern Europe.

Toward the Soviet Union, in particular, Kohl sounded a bit more guarded than had Schmidt. The new chancellor said he would "not overlook the severe obstacles and setbacks" to East-West relations resulting from the Soviet invasion of Afghanistan, the situation in Poland and Moscow's arms buildup. He promised to use every opportunity to "press for positive changes."

There was no mention of the controversial natural gas pipeline project from Siberia to Western Europe. Bonn officials have already made clear that German commitments for the project will be honored under Kohl. In fact, Kohl asserted that his government regards a continuation of German trade with the Soviet Bloc as an "important part" of East-West relations.

Differences between West Germany and the United States over East-West trade policy, defense spending and economic relations have soured ties between the two major allies in recent months. Kohl said today that friendship with the United States and Bonn's attachment to the Western Alliance were the "fundaments" of West German foreign policy. "We will free German-American relations from all doubt and confirm and stabilize our friendship," he said, without stipulating how this would be done.

Announcing his intention to travel to Washington soon -- aides say it will probably be in November -- Kohl said the aim of the visit will be to intensify consultations and "expand bilateral exchange at all levels."

On nuclear arms, Kohl made clear his government's intention to accept the stationing of new U.S. nuclear missiles if U.S.-Soviet negotiations in Geneva on reducing such weapons fail by the end of 1983. Unlike Schmidt, who in his last months would speak of the need to nudge both the Soviets and the Americans to negotiate seriously, Kohl limited his appeal to the Soviet Union.

Kohl's remarks, some of which were bound to irritate the right, were clearly pitched at the political center, and the chancellor spoke repeatedly of his new government as "the coalition of the center."

His 90-minute statement, which met with frequent heckling from Social Democrats bitter about a change in government they see as tainted by political intrigue, was devoted chiefly to his top priority: solving West Germany's economic troubles.

Declaring that his government had inherited "the most severe economic crisis in the history of the Federal Republic of Germany," Kohl said the new coalition had taken power to avoid the "decline from becoming a crash." He asked the public to brace for sacrifices and accept a "breathing space" in social-welfare spending by the state.

The government has already outlined a controversial package of tax increases and welfare program cuts designed to save more than $5.2 billion next year, stimulate business investment and revive housing construction. Kohl warned that the economy could get worse this winter -- with unemployment rising to 2.5 million from the current 1.82 million, or 7.5 percent of the work force -- before it gets better.

"The question of the future is not how much more the state can do for its citizens," he said. "The question of the future is, how can freedom, dynamism and self-responsibility develop in new ways?"

Kohl's emphasis throughout was on conservative principles -- less state intervention in society and more freedom and self-reliance for the individual. "We have come to a crossroads in our development," he said. "We must decide in which direction we want to continue . . ."

Acknowledging that he could not give a traditional government policy statement because his coalition is still tentative, Kohl renewed his pledge to try for new national elections March 6. But he left vague how he intended to overcome the constitutional problems that complicate the calling of new elections before their scheduled time in 1984. Instead, Kohl proposed all-party talks to consider the issue.