West German Chancellor Helmut Schmidt and East German Communist Party chief Erich Honecker have postponed a meeting originally planned for early this year, the two governments announced today.

The action was a clear signal that the strained relations between the United States and Soviet Union have seriously disturbed efforts by the two Germanys to continue their own detente.

It also marked a setback for Schmidt, whose Social Democratic Party has pursued a policy of detente with Eastern Europe and who is having to defend that policy in national elections this year.

The planned meeting would have been the first East-West German summit on German soil in nearly a decade. It had been announced in a surprise statement by Schmidt last month. He did not specify where the meeting would take place or when. Again this month and despite the Soviet invasion of Afghanistan -- the chancellor had reiterated his desire to meet early this year with party chief and President Honecker.

But, today, government spokesman Armin Grunewald said the two leaders had agreed not to set a date for the meeting at this time. He said both sides still wished to have the meeting and a date would be set "during the course of the year."

In East Berlin, the officials news agency reported the postponement in nearly identical language. However, the West Germans said the suggestion to postpone the meeting had come from East Germany, which wanted "to keep the date flexible."

Privately, aides close to Schmidt said they were of the opinion that the motion for a postponement had come from Moscow. All along, the apparent willingness of Honecker to meet with Schmidt was recognized here as requiring Kremlin approval.

In view of the cooling of relations between the superpowers, Schmidt had nonetheless remained hopeful that the Soviets would grant approval. Some West German officials fostered the notion that the West-East German tie could be used by the United States and the Soviet Union, as a convenient line of communication to pursue European disarmament talks and other concerns.

For Moscow, the link between the Germanys has been seen by some observers here as at least a valuable pressure point on the West. Indeed, by delaying the meeting, the Soviets may be sending a signal that they are prepared to make things uncomfortable for America's European allies.

There is also a report -- unconfirmed but mentioned during interviews with several senior Bonn officials -- that Moscow had been holding the Schmidt-Honecker summit as ransom until Schmidt agreed to fix a date for a meeting in Moscow with President Leonid Brezhnev. The chancellor had declared that intention earlier this month but no date had been set for that meeting either.

The White House, while not objecting to a summit between the two German chiefs, is known to have been cool to the idea of a Schmidt-Brezhnev meeting at this time.

Three other trips by West German officials to Eastern European countries have been postponed or canceled in recent days. Economics Minister Otto Lambsdorff delayed a visit to Warsaw after the Poles put forward a new list of themes they wished to discuss. A planned trip by Foreign Minister Hans-Dietrich Genscher to Czchslovakia was scratched and so was a scheduled trip by Labor Minister Herbert Ehrenberg to Moscow, officially because of difficulties of timing.

At the same time, leading opposition politican Franz Josef Strauss -- who is running against Schmidt this autumn -- visited Romania last weekend and Hungary's foreign minister is expected in Bonn next week.

"We don't see exactly what the policy is on the other side," said a foreign policy planner. This official added that it is perhaps to the Soviets' advantage to keep their signals to the West unclear so long as there is talk about an Olympic boycott and other sanctions resulting from the invasion of Afghanistan.

Schmidt and Honecker had a brief informal meeting during the 35-nation European Security Conference in Helsinki in 1975. The last official talks between leaders of East and West Germany were nearly a decade ago, when Willy Brandt, then West German chancellor, and Willi Stoph, then East Germany's prime minister, met twice within two months.