The Soviet government news agency Tass voiced the hope tonight that President Reagan's decision to resume strategic arms talks with Moscow was not caused by "fleeting political considerations" but by a "sincere striving" to secure peace.

In the first response to Reagan's Memorial Day speech, Tass welcomed his assertion that the United States would take no actions that would undermine the Soviet-American strategic arms limitation treaty, SALT II, which has not been ratified by the Senate.

The moderate and somewhat optimistic tone of the Tass commentary stood in contrast with a pessimistic private assessment about the prospects for agreement at the Geneva talks due to start June 29.

Sen. Larry Pressler (R-S.D.), here on a six-day visit, told reporters he found a "great deal of skepticism" about American intentions in his talks with senior Soviet officials, including Viktor Karpov, who is designated to be the chief Soviet negotiator at Geneva.

Pressler said the Soviets made it clear that they expected to conduct protracted and difficult negotiations at Geneva. He quoted a ranking Foreign Ministry official, Viktor Komplektov, as saying about the talks, "You've got yourself a 10-year job there."

Pressler said he was surprised by Karpov's willingness to discuss on-site inspection of provisions to be reached at the Geneva talks. The issue of on-site verification has been a major obstacle in previous strategic talks.

Pressler said Karpov had told him that Moscow was against any "extensive linkage" of other political issues to the substance of the Geneva talks.

Pressler also met with Soviet agricultural specialists and said the Soviets were interested in a long-term agreement on purchases of American wheat and grain.

In contrast with public pronouncements about Moscow's intentions to reduce grain imports from the United States, Pressler said he was told by top officials of the Ministry of Agriculture that the Soviet Union would have to maintain their imports at the current level for the "foreseeable future."

As a senator from a farming state, Pressler said he strongly favored U.S. grain exports to the Soviet Union and that he had sought to persuade the Soviets that "we are embargo-proof now." He said his interlocutors repeatedly complained about the "unreliability of American supplies."

Pressler is chairman of the arms control subcommittee of the Senate Foreign Relations Committee.