Three days before he travels to Moscow for a crucial summit with Soviet leaders, West German Chancellor Helmut Kohl met here today with chief U.S. arms negotiator Paul Nitze and later expressed hope that a compromise on medium-range nuclear missiles in Europe might be struck with the Soviets by the end of the year.

While the Geneva negotiations still appear deadlocked, West German officials said Kohl and Nitze saw some hopeful signals Tuesday in a Warsaw Pact communique that advocated a negotiated accord before the West begins deployment of 572 Pershing II and cruise missiles in Western Europe in December.

The Warsaw Pact declaration, issued after a one-day gathering of bloc leaders, endorsed the Soviet position in Geneva but refrained from threats that Moscow would station nuclear rockets in East Germany and Czechoslovakia in retaliation for western deployment of new missiles in Europe.

West German officials said they viewed the omission of such threats as a positive development, perhaps a harbinger of new Soviet willingness to seek an acceptable compromise in the Geneva talks.

Some officials in Bonn have speculated that the Soviets might unveil a new arms control initiative when Kohl visits Moscow next week. They noted that on the occasion of then-chancellor Helmut Schmidt's trip there three years ago, the Soviets reversed their position and announced they would join the United States in the Geneva negotiations.

The Reagan administration has become intimately involved in preparations for the Soviet-West German summit, reflecting the importance Washington attaches to Kohl's journey at a crucial stage in East-West relations.

During a visit to Krefeld, West Germany, on Saturday, Vice President Bush discussed the Moscow visit in depth with Kohl and gave him a letter in which President Reagan offered "full personal support" for Kohl's mission.

West German Foreign Minister Hans-Dietrich Genscher discussed the trip with Secretary of State George P. Shultz in Bangkok this week during a conference of Southeast Asian nations. They agreed that Genscher should fly to Washington July 11 to report on the results of the Moscow meetings.

The new flashes of optimism about the Geneva talks contrast sharply with Kohl's earlier remarks, made as recently as the Bush visit, that only a "miracle" would salvage an arms agreement and prevent deployment of new missiles in West Germany later this year.

Egon Bahr, the opposition Social Democrats' disarmament expert, returned from Geneva today after talks with Nitze and his Soviet counterpart, Yuli Kvitsinsky, and said he gained the impression that no real negotiations were taking place.

He said that Soviet insistence on counting French and British deterrent systems in the talks had blocked progress, and he suggested that only a meeting between Reagan and Soviet leader Yuri Andropov could achieve a breakthrough.

Kohl also met today with Max Kampelman, the U.S. representative at the Madrid Conference on Security and Cooperation in Europe.

Bonn has been pressing for a resolution of the three-year-old negotiations in Madrid in order to launch a follow-up conference on European disarmament by the end of this year.

The Madrid conference has been stymied by sharp disagreement between the United States and the Soviet Union over human rights declarations. West Germany strongly supports a compromise proposed by the Spanish government and hopes that a breakthrough may be achieved by the time Kohl returns from Moscow.