West German Foreign Minister Hans-Dietrich Genscher, here to inform President Reagan about last week's talks in Moscow between Chancellor Helmut Kohl and Soviet President Yuri V. Andropov, said yesterday that Bonn believes a U.S.-Soviet summit meeting could have a "favorable" effect on East-West relations.

Speaking with reporters after his White House meeting, Genscher said:

"It turned out in Moscow that direct talks with the Soviet leadership have a positive effect on forming opinion in the Soviet Union. This is why the federal chancellor and I believe that meetings of that kind are very favorable, that meetings between the American and Soviet leaders would be favorable."

However, he qualified his support for a Reagan-Andropov summit by reiterating that Bonn agrees with conditions that the United States has said are necessary for such a meeting.

Any summit, he agreed, should be "well-prepared" and should offer "a prospect of positive results."

By using that qualification, Genscher brought the West German government's well-known enthusiasm for a summit into line with the Reagan administration's wariness about high-level meetings that might raise expectations without producing substantive agreements.

As a result, a senior U.S. official, who met with reporters later on condition that he not be identified, endorsed Genscher's remarks as being in line with U.S. policy.

"We support his overall concept in East-West relations of firmness on one hand and readiness for dialogue on the other hand," the senior official said.

Kohl had hinted in Moscow that the Soviets may have new ideas for breaking the deadlock in U.S.-Soviet negotiations on limiting medium-range nuclear weapons in Europe. However, U.S. and West German officials, while declining to be specific, said yesterday that Kohl had not returned from Moscow with any proposals that seem likely to produce dramatic or sudden results in the Geneva talks.

Genscher did create a brief stir when he left the White House and made a statement in German that an interpreter translated into English in this way:

"It is our hope and expectation that the Soviet Union will no longer block these negotiations by wanting to take into consideration the French and British systems."

The word "expectation" led to some news agency reports stating that West Germany expects Moscow to drop its demand that any agreement on limitations should take into account British and French nuclear weapons as well as the U.S. Pershing II and cruise missiles scheduled for deployment in December. The Soviet position on the British and French systems has been a major sticking point at Geneva.

However, his words, when listened to in German, left the impression that he was only expressing a hope about what the Soviets might do in Geneva rather than predicting a change in their stance.

The senior U.S. official said later that he was unaware of any such prediction by Genscher in his talks with Reagan or Secretary of State George P. Shultz, and added that he did not believe that was "an accurate depiction" of Genscher's views.

In general, the official continued, Genscher's report had not given the United States any grounds for believing that there is "a hard new Soviet negotiating position." The official described Moscow's "bottom line" as wanting to "maintain a complete monopoly" on medium-range missiles in Europe, and said, "That's totally unacceptable to us."

According to reports from Bonn last week, Andropov told Kohl that he favored extending by a week or two the Geneva talks, which are to adjourn Thursday for two months, and resuming them Sept. 8. However, the U.S. official said that "we heard nothing about that" in yesterday's talks with Genscher, and said the Geneva talks will recess Thursday as scheduled.

Genscher also told reporters that the only way to delay deployment of the new U.S. missiles in western Europe would be Soviet acceptance of Reagan's call for elimination of all medium-range weapons from the continent.

The Soviets have rejected this so-called "zero-option" plan.