U.S. officials said yesterday that they have begun work on a "prospective agenda" for a summit between President Reagan and Soviet leader Mikhail Gorbachev with the expectation that a meeting will take place this fall.

While emphasizing that the Soviets have not agreed to a date or place for a summit, the officials said work on the agenda has begun so that it can be discussed by Secretary of State George P. Shultz and Soviet Foreign Minister Andrei Gromyko when they meet in Vienna May 14.

Under preliminary consideration for inclusion on an agenda, officials said, is a new "declaration of principles" similar to the one signed by President Richard M. Nixon and Leonid Brezhnev when they met in Moscow in 1972.

That declaration, in which both superpowers agreed to general principles of peaceful coexistence, mutual restraint and regular summit meetings, was symbolic of the era of "detente," a word Reagan once used as as a term of opprobrium.

Reagan invited Gorbachev to a summit meeting in Washington soon after he replaced the late Konstantin Chernenko as Soviet leader. In an interview Monday with The Washington Post, Reagan said that Gorbachev had replied to the letter, and that U.S. officials termed the response a positive one in which the Soviet leader had agreed in principle to a summit meeting.

Subsequently, U.S. officials said they anticipate a summit either in September or October, when Gorbachev is expected to attend a meeting of the United Nations in New York. These officials said the president is willing to meet Gorbachev at the United Nations rather than in Washington, if that is the Soviet preference.

Publicly, both Shultz and Gromyko have been trying to dampen expectations for a summit. Gromyko was quoted by Canadian Foreign Minister Joe Clark as saying to him Wednesday in Moscow that the Soviets "certainly were nowhere near choosing a date or a venue" for a meeting.

Shultz told a Senate subcommittee that U.S. officials were "devoting a lot of attention" to a summit, but said, "My opinion is that a pure-and-simple get-acquainted session is not the way to go."

Reagan has been criticized by conservative supporters for his restrained response to the killing of U.S. Army Maj. Arthur D. Nicholson Jr. March 24 by a Soviet guard in East Germany. An administration official said yesterday that this view had been "strenuously represented" within the White House by Patrick J. Buchanan, the president's director of communications.

The president is sensitive to this criticism but has tried to turn it into an argument for a summit. In the interview Monday, he called the shooting of Nicholson "a cold-blooded murder" but said it made him want a summit "even more so, to sit down and look someone in the eye and talk to him about what we could do to make sure nothing of this kind happens again."

However, an official emphasized yesterday that Reagan is committed to a summit "without preconditions" and that the administration expected that "sooner or later" the Soviets would respond to Gorbachev's letter by suggesting a date and place.