West German officials here and in West Berlin are "a little bit nervous" over a "town meeting" that President Carter is to conduct in West Berlin next Saturday with about 1,000 residents of the western half of that divided city.

Although the Bonn government is looking forward to the first state visit by President Carter, what concerns the West Germans is the format of the president's appearance in West Berlin.

Rather than make a prepared speech to the West Berliners, as previous American presidents have done during visits to the city, Carter will answer questions that are posed by the audience.

In such a forum, the West Germans are worried that the president might not have enough time to think about the impact of his words and could slip or say something about West Berlin or allied policy toward the city that could have important East-West repercussions.

Berlin has faded somewhat as the rallying point that it was for Americans in the period of the Cold War and the 1948 Berlin airlift. Nevertheless, the fate of the divided city remains an extraordinarily sensitive issue to the West Germans and to allied officials responsible for trying to keep it thriving as a Western outpost 125 miles deep inside East Germany.

Official communiques on the city's status by the three allied powers - the United States, France and England - are always considered word-for-word before they are issued, with the West Germans sitting in on meetings where such statements are developed.

At the NATO summit meeting in London last May, the president made a mistake in discussing the Berlin situation with reporters when he alluded to West German and East German patrols operating in each others sector of the city. A correction was issued later, and the matter was not viewed as serious by Bonn at the time, but it is clearly being recalled these days as the type of thing that could go wrong, on a larger scale.

The Communist government of East Germany and the Soviet ambassador to East Germany have been responsible for a steady stream of commentaries that suggest the 1971 four-power agreement on Berlin does not apply to East Berlin, which the communists claim as the capital of East Germany. There have been steady, and frequently successful efforts by the East Germans and Soviets to erode Western rights in the eastern zone.

West German sources say reports reaching here from Washington indicate that the White House chose the town meeting format because the president is more effective and impressive in a question-and-answer setup than as a stand-up speechmaker and also that Carter wanted "to do something different" than other presidents who have visited the city.

Although the guests to the town meeting are invited and are meant to reflect all walks of life in West Berlin, the White House reportedly has insisted that the questions not be submitted beforehand and that the whole meeting, which will be televised live, must be spontaneous.

There also reportedly was concern and opposition to the format among some State Department officials in Washington. Western officials here believe many of the questions will be on East-West matters other than Berlin and that the president will be well prepared to handle things.

The president's trip to West Berlin is part of a two-day state visit to West Germany that begins Thursday night and then will lead into the economic summit meeting of seven Western industrial nations that opens here on Sunday.

Chancellor Helmut Schmidt is to accompany the president to West Berlin, a move that also is expected to draw a perfunctory Soviet protest. Schmidt will also join Carter earlier that day in a trip to meet with U.S. and West German soldiers in the Wiesbaden area.

The West German government, like other governments in central Europe, is deeply concerned over the steadily worsening relations between the United States and the Soviet Union.

The Bonn government has been trying to maintain good relations with the East, since West Germany is on the front line between blocs and has major trade and personal links to the East. Schmidt was recently host to Soviet President Leonid Brezhnev on a state visit here.