The impact of an Italian Cabinet minister's accusations that a Soviet Bloc state was involved in the attempt to assassinate Pope John Paul II has been significantly tempered here by the conviction that his charges were at least partly related to domestic Italian politics.

Socialist Defense Minister Lelio Lagorio described the May 1981 attack on the pope as "a true act of war in peacetime" and as "a precautionary and alternative solution to the invasion of Poland."

His position on the purported "Bulgarian connection" to the shooting, and the alleged Soviet interest in encouraging it, was far stronger than that of any of the three Christian Democratic ministers who also testified in parliament last month.

As such, his speech made headlines in much of the Western world. Neither Italian magistrates nor the government here has made public specific details of the evidence against three Bulgarians implicated in the shooting, and the minister's hard-hitting speech was taken in some quarters as suggesting that the government as a whole was convinced of a Soviet Bloc plot in the case.

Here in Italy, however, many Italian and foreign observers tend to view Lagorio's statements with a grain of salt. While acknowledging that Lagorio's accusations may prove to be correct once all the evidence is made public, politicians from other parties as well as government officials have pointed out that he failed to support his harshest accusations with substantial proof. They have described his comments--which also touched on alleged Bulgarian involvement in Italian terrorism and in arms and narcotics smuggling--as "hasty" and "irresponsible."

The observers say that the Socialist's outspoken statements must be viewed in the context of the Socialist Party's vigorous competition with both the Italian Communists and--even more--with the Christian Democrats, the Socialists' coalition partners and major political rivals.

"It's not unreasonable to assume that the Socialists would see an advantage in making political hay out of this issue," said one western diplomat who follows the party closely.

He explained that by "pointing the finger at the Soviets," the Socialists could embarrass the more powerful Communists, with whom they compete for some votes, and also demonstrate their dynamism and reliability to more conservative voters who in the past have supported the dominant Christian Democrats.

"By defending the pope, the Socialists also appear to be going after the support of left-wing Catholics," said a Foreign Ministry official who asked that his name not be used.

The Socialists, bolstered by electoral successes of fellow Socialists in France, Spain and Greece, currently are making a major bid to attract voters. Both the diplomat and the Foreign Ministry official pointed out that in recent months the Socialists have increasingly sought to use foreign policy issues to boost their image as a dynamic, independent and thoroughly pro-western party.

Since Lagorio's speech, Foreign Ministry officials emphasized that Italian foreign policy is officially enunciated by Foreign Minister Emilio Colombo, a Christian Democrat, who has consistently treated the Bulgarian question with caution.

Lagorio's outspokenness flew in the face of Italy's traditional wariness in foreign policy, an unwritten rule of which always has been to avoid breakdowns in bilateral international relations.

Early last month, Colombo recalled the Italian ambassador from Sofia and in the parliamentary debate said visa restrictions and a reduction of the Bulgarian Embassy staff might be considered. He acted after the arrest in Rome of Bulgarian airline official Sergei Ivanov Antonov, who was charged with "active complicity" in the shooting, and announcement that two other Bulgarians were suspected of involvement in the case. Colombo stressed, however, that further action would be legitimate only "when suspicions became certainties."

The three Christian Democrat ministers--of foreign affairs, justice and interior--who testified acknowledged that there was ample reason to suspect Bulgarian individuals of involvement in the papal assassination attempt and in other cases involving espionage, Italian terrorism and arms and drug smuggling. But only Lagorio suggested the existence of one or more plots by East Bloc states. He insinuated that Italian secret services have indicated that East Bloc countries had had links with Italian terrorists.

Lagorio also said that Italian secret service agents met convicted papal assailant Mehmet Ali Agca a year ago and tried to convince him to talk; that they gave chief investigator Judge Ilario Martella information last July on two Turks suspected of involvement; and that a month earlier they gave Martella an album of photographs of suspect foreigners. Lagorio said that Agca was shown the photographs in September and he "indicated three Bulgarian Embassy officials as his accomplices."