Nicaragua said today that an effort to obtain the release of eight West Germans kidnaped by antigovernment guerrillas had failed, and blamed the United States.

A Foreign Ministry official, explaining a brief communique on the failed effort, said an arrangement had been made by Nicaragua and the United States for the Germans to be handed over to a West German envoy yesterday. The official said the envoy, Social Democratic politician Hans-Juergen Wischnewski, flew to the isolated Nueva Guinea region where the release was to take place, but did not find the Germans, volunteer construction workers who were kidnaped by the rebels May 17.

A U.S. Embassy official here denied that the U.S. government was involved in any negotiations, saying, "This is a matter between Nicaragua and the German government." The Nicaraguan government holds the United States responsible for the actions of the rebels, known as counterrevolutionaries or contras, because they have received aid from Washington.

In Washington, Gregory Lagana of the State Department's inter-American affairs bureau said Sandinista forces had increased military pressure in the area where the Germans were held, delaying the cease-fire that had been arranged for the transfer of the captives. Then, he said, the Sandinistas sent the helicopter that was to pick up the captives to the wrong place.

In Tegucigalpa, Frank Arana, a spokesman for the Nicaraguan Democratic Force, the main rebel group, said the Sandinistas had violated the truce and attacked the rebel force holding the Germans, The Associated Press reported.

Nicaragua's Defense Ministry denied the reports that Sandinista forces had been attacking in the Nueva Guinea region.

West German Foreign Minister Hans-Dietrich Genscher and Secretary of State George P. Shultz discussed the matter on the telephone yesterday, West German and U.S. officials said.