A Soviet attempt to steer a major Italian art festival away from the theme of dissidents in Eastern Europe has triggered resignation of its director and charges of Soviet interference embarrasing to the Italian Communist Party.

Socialist Carlo Ripa di Meana resigned from the state-subsidized but independent Venice Biennial last night, saying that the Foreign Ministry has advised him to find a "diplomatic" way to accommodate the Soviets.

Ripa di Meana was summoned to the ministry after Soviet Ambassador Nikita Rizjov presented a protest that Ripa di Meana said included a threat to pull out the biennial - along with East European countries - if the show's theme is not changed.

The Communist Party, now Italy's second largest, was caught in the middle in seeking to convince voters of its independence from Moscow. The party recently has been attacked for failure to take a stand on the human rights cases in the Soviet bloc.

Deputy Aldo Tortorella, the Communist spokesman for cultural affairs, said the Venice show "must continue its work in full autonomy" and without "foreign interference." He said, "The statements of the Soviet ambassador ought not to have influence on the organization's decisions."

Asked about charges that the Communist reaction was "too weak," a party officials said he thought the incident was being used to stimulate "a new form of anti-communism." He noted that Ripa is Meana's Socialists are appealing to the voters as being more willing than the Communists to defend human rights.

The festival's theme of cultural dissidence in Eastern Europe was announced several weeks ago and approved by the board, which includes representatives of all major parties. The program was to include paintings and sculpture by dissidents who have left Eastern Europe as well as representatives of the official cultural throught there.

In recent years the festival has often taken on leftist overtones, most recently focussing - with active Soviet participation - on anti-fascist dissent in Generalissimo Franco's Spain and in Chile.

Foreign Minister Arnaldo Forlani issued a statement today saying that communication of the Soviet message to Ripa di Meana had been "purely informative."

But the influential Turin daily La Stampa asked editorially whether the Soviet foreign policy of "limited sovereignty" in Eastern Europe was "already" being applied to Italy, where the Communists give crucial parliamentary support to the current minority Christian Democratic government.

One of Italy's best-known political commentators and Soviet-watchers said the "whisky-washy" attitude of the Italian ministry "gave the impression our country is about to be turned into another Finland" - that is, into a country formally independent but subject to Soviet influence.

Adding to the Italian Communists' discomfort were reports here that the party has insisted on deleting the dissidence issue from a joint declaration in Madrid yesterday by the Italian, French and Spanish Communist leadership.