Soviet official silence on the seizure by the U.S. Coast Guard of two Russian fishing trawlers in recent days probably reflects Moscow's desire to settle the sensitive matter with a minimum of fuss, according to informed Western sources here.

That view, however, is based on contacts with Soviet Ministry of Fisheries officials before the warning by the White House yesterday that continued violation of U.S. fishing restrictions by the Russians would be harmful to Soviet-American relations.

President Carter's intervention could yet raise the seizures to a political level here that will add another point of friction to already strained U.S. Soviet ties.

Spokemen for the Fishing Ministry would say only that the circumstances of the seizures is being investigated.

In meetings with Americans last week, the Soviets were understood to have adopted a generally conciliatory stance on the dozens of violations by Soviet ships of an agreement with the United States on conditions for fishing inside the U.S. 200-mile zone.

U.S. source said that the Soviets pointed out that restrictions had gone into force only on March I and that some captains may still not understand all the limitations on them. The Soviets said they would take measures to see that violations were halted as soon as possible, the sources reported.

The establishment in recent months of the 200-mile fishing zones by most North Atlantic countries and Japan has affected the Soviet Union more than any other country because the world's largest fishing fleet and 60 per cent of its catch from what are now other people's waters.

Moscow has also adopted a 200-mile zone in an effort to improve its bargaining position with the other countries that have recently extended their claims to coastal waters. Negotiations on reciprocal agreements with the European Economic Community and Japan are under way.

Moscow had been adamant in its refusal to talk with the EEC as a bloc - which amounts to a form of recognition of the community - but faced with no alternative, the Soviet position had been that it would make agreements only with individual governments.

The Japanese talks are equally complicated and have renewed political tensions between Tokyo and Moscow. The core of the problem is how to delincate the fishing zone around four islands north of Japan seized by the Soviets at the end of World War II. Japan has long demanded their return.

A fighing agreement with the United States awas reached last fall, the Soviet's first such accord with another country. U.S. ships do not operate in Soviet waters so the question of possible American violations does not arise.