The Soviet Union sent a new warning signal to the Polish government tonight as it continued to assail "antisocialist forces" in Poland. It cautioned that "one must" clearly separate "authentic workers' demands from antisocialist intrigues."

The government newspaper Izvestia pointedly omitted any references to the settlement reached yesterday by the Polish authorities and striking workers although the news agency Tass had distributed earlier today a brief report that an accord on unspecified "socioeconomic questions" had led to the resumption of work at Gdansk and other Polish Baltic Coast cities.

East European diplomatic sources here said that Soviet reactions on the sweeping Polish labor agreements indicated a complete Kremlin rejection of Communist Party leader Edward Gierek's concessions on the issue of trade unions. Moscow is somewhat relieved that the workers are back on their jobs, one senior diplomat said, but feels that the Polish crisis is far from over.

In this view, the Polish strike and its settlement constitute the most important internal development in the Soviet Bloc since Moscow extended its empire into Eastern Europe at the end of World War II.

Although they started as protests over meat price increases, the Polish strikes have mushroomed into a mass movement with a coherent leadership and goals. The strikers were no longer content with minor economic adjustments, as they were during earlier waves of strikes in Poland, but instead insisted on and won broad economic and political concessions from a beleaguered communist government.

From Moscow's viewpoint, this sets a new and dangerous precedent for the entire Soviet Bloc, which is entering a period of increased economic difficulty. Shortages of meat and foodstuffs have recently produced work stoppages in the Soviet Union itself.

As a result, according to East European diplomats, the way the Polish leadership goes about resolving the crisis -- and especially whether it does in fact accept an organized labor movement outside the Communist Party -- is watched with serious anxiety and clear reservations here.

Izvestia charged today that "antisocialist forces" seeking to take over the labor movement now want to gain "official recognition for an antisocialist opposition." The opposition's objective, it said, was to be treated "as partners" by Polish authorities, but its long-term goal was "to completely change the political structure of Poland."

The criticism was clearly aimed at the crucial issue of independent trade unions, the major concession granted by Gierek but not mentioned thus far in the Soviet media.

An authoritative commentary in Pravda, the Communist Party newspaper, referred to the same issue this morning when it described it as an attempt to damage socialism and "violate" the key link between the working class and the party. It said this link was the source of the party's power.

Diplomats here interpreted the strongly worded articles in Pravda and Izvestia as a warning to Gierek and his colleagues to hold the line. "So far," one source said, "nothing has been settled."

In the view of those familiar with Kremlin thinking, Soviet intervention in Polish affairs would be a measure of last resort. However, these diplomats noted that. Gierek's position in Warsaw has deteriorated and he may soon be replaced.

Any direct Soviet involvement would come only if the Poles begin to question the two basic policies -- Poland's socialist system and its role in the Warsaw Pact. So far, even dissident workers have not challenged either policy.

Nevertheless, there are fears here of long term damage that could spill over should the strike settlement be implimented completely.

Tonight, Izvestia singled out the Workers' Defense Committee as one of the "antisocialist" groups that was seeking to undermine socialism "from within." There was implicit criticism in this of the Gierek government's dealings with independent groups. The paper named Jacek Kuron and Adam Michnik as being the organizers of the antisocialist campaign. Both Kuron and Michnik were released from jail earlier today as part of the strike settlement.