After enduring a period of estrangement imposed by the Soviet Union, West Germany apparently has launched a new diplomatic offensive to improve relations with its East European neighbors.

West German Foreign Minister Hans-Dietrich Genscher's whirlwind tour through Moscow, Warsaw and Sofia this week, following earlier visits to Prague and Bucharest, is intended to dispel the impression that the Soviet Union can freeze Bonn out of East-West diplomacy as a punishment for deploying Pershing II missiles on its soil.

Genscher's trip is also aimed at defusing the wave of propaganda attacks accusing Bonn of seeking to regain East Bloc territories that were once part of the Third Reich. West German officials expect the hostile charges to intensify in the weeks leading up to the 40th anniversary, on May 8, of the defeat of Nazi Germany.

But Bonn policy makers said Genscher's quest for dialogue with all East Bloc states also reflects a more fundamental change in Bonn's diplomatic tactics toward Eastern Europe.

By pursuing a policy of building separate relationships with East Bloc states across the board, Bonn believes it can deflect the kind of intimidation from Moscow on individual capitals that led to the cancellation of trips to West Germany last year by the leaders of East Germany and Bulgaria.

Genscher's meeting with Soviet Foreign Minister Andrei Gromyko on Monday, regardless of the content or tone of their exchanges, is being considered a success here because "other Warsaw Pact states will now see that our days of isolation are over and it is no longer politically troublesome to talk with us," a senior official here said.

At the same time, Chancellor Helmut Kohl's government sees a possibility of extracting greater cooperation in the future from East Germany by making the Communist authorities there "feel the competition" from East Bloc allies eager to reap the potential economic benefits of dealing with Bonn, officials said.

Last September, after several months of surprising rapprochement between the two Germanys at a time of protracted East-West tensions, East German President Erich Honecker bowed to Soviet pressure and canceled his long awaited trip to West Germany. Later, Bulgarian President Todor Zhivkov also dropped plans to visit Bonn.

The experience reminded the Kohl government not only that it must work with Moscow if it hoped to restore detente with Eastern Europe, but that too much emphasis on the German-German relationship evokes poisonous suspicions throughout the rest of the East Bloc.

Bonn officials said they realize now that the exaggerated expectations aroused by the glare of publicity on the two Germanys only contributed to the pressures on Honecker to put off the visit.

Since that time, East Germany has acted with great caution in its approaches toward Bonn and has dutifully, if reluctantly, joined its East Bloc allies in the campaign against Bonn's alleged territorial designs on Eastern Europe.

With East Germany still shying away from enhanced ties with Bonn, Poland has become one of the key priorities in West Germany's new diplomatic approaches toward the East Bloc.

Last week, Kohl sought to alleviate tensions with Warsaw by rebuking right-wing members of his party who insist that postwar borders are still undecided and that Silesian areas of western Poland are still German. In his annual state of the nation address, Kohl said West Germany accepted present frontiers and would faithfully abide by its treaties signed with Soviet Bloc states.

Kohl's conciliatory statements prepared the ground for Genscher's six-hour stopover in Warsaw on Wednesday, where he is to see Gen. Wojciech Jaruzelski and the foreign minister, Stefan Olszewski.

The meetings are expected to lead to a full-fledged official visit soon by Genscher, who postponed a trip to Warsaw in November at the last minute because the Polish authorities objected to his plan to place a wreath at the grave of the slain pro-Solidarity priest Jerzy Popieluszko.

The West German government was helpful in rescheduling Poland's debts and is contemplating the possiblity of securing new credits for Warsaw.

Bonn has also received encouraging signals from Bulgaria, Hungary and Czechoslovakia that they are ready to make substantial steps toward improved trade and economic relations.