The United States is closely monitoring preparations for military maneuvers by Soviet-bloc forces in East Europe for signs that the exercises could be part of a future intervention in Poland.

State Department spokesman and other senior officials, however, said there was no indication at this time that these maneuvers would be part of any imminent Soviet invasion. The information being gathered by Western intelligence is still "ambiguous," sources said.

The Soviets may be preparing for a "command post exercise," which mainly involves tests of communications between military headquarters, or could be readying something involving maneuvers with thousands of troops.

Sources said there are some indications that the first part of the exercise could start this weekend and involve units in East Germany, Czechoslovakia and the Soviet Union. A second phase, possibly involving Polish forces or Soviet forces already based in Poland, might come later.

A massive buildup of Soviet forces has taken place along the Polish border since last December as labor unrest in Poland challenged communist authority and threatened to get out of hand.

Although Moscow has made no further move, U.S. specialists long have believed that any military action would come in the guise of a joint Warsaw Pact maneuver that would bring many more Soviet divisions into Poland to augment the two divisions permanently stationed there.

In confirming reports of the preparations, State Department spokesman William Dyess reiterated the U.S. view that an invasion "is not imminent, inevitable or justifiable on any grounds."

Dyess said: "Poland should be free to solve its own problems without outside interference" from any nation. He repeated U.S. warnings that such interference would have "grave consequences" for East-West relations.

Dyess also pointed out that Warsaw Pact maneuvers normally occur at this time of year and that they probably would not have "raised any eyebrows" were it not for the tense situation inside Poland.

Other officials said the maneuvers had been planned long before the meeting in Moscow Wednesday between Polish and Soviet leaders.

Under terms of the 35-nation Helsinki agreement, the Soviets are supposed to give the West 21 days' notice of maneuvers involving more than 25,000 troops and are "encouraged" to give notice of smaller exercises. Thus far, officials said, no notice has been given.