West Germany today charged a Soviet official with violating "international custom and good manners" by publicly pushing Soviet policies during an ostensibly private visit here.

Bonn spokesman Kurt Becker suggested the official seemed to be trying to undermine Bonn's position on the latest Soviet peace offers. The expression of irritation reflected suspicions among West German officials about the motives behind the Kremlin's latest overtures to the Western alliance.

The case in point was a press conference in Bonn on Monday by Georgi Arbatov, chief of Moscow's Institute for Studies on the United States and Canada and an adviser to Kremlin leaders. While ostensibly here to promote the German edition of his new book, "The Soviet Position -- Western Policy of the USSR," Arbatov took the occasion to elaborate on the idea of a moratorium on the deployment of nuclear missiles in Europe and on other proposals floated by Soviet President Leonid Brezhnev at last month's Communist Party congress in Moscow.

The Bonn government had rejected the moratorium idea, saying it would mean accepting Soviet nuclear superiority in Europe. Bonn official saw the proposal as a gambit by Moscow to go over the heads of Western governments and arouse West European public opinion against plans by the Atlantic Alliance to deploy U.S.-made medium-range nuclear missiles in Europe, a move intended to offset the recent buildup of Soviet SS20 missiles.

In his press conference, Arbatov said he was surprised and dismayed that Bonn had not taken Brezhnev's moratorium proposal seriously. He said that the idea of a freeze applied only to deployment, not production, of the missiles and urged the West German government to reconsider.

Becker objected to Arbatov's interpretation and to the practice of Soviet officials of making public policy statements while on private visits in the West.