Soviet President Leonid Brezhnev voiced limited confidence today that Poland's Communists can achieve full control over the country, omitting in his speech to the Czechoslovak Communist Party Congress references to possible Warsaw Pact intervention that have been prominent in Eastern European capitals in recent days.

Later today, the official Soviet news agency Tass announced that the Soyuz 81 Warsaw Pact war games in and around Poland had ended after three weeks of maneuvers, thus removing a major cause of Western concern about Moscow's immediate intentions toward its troubled ally.

In his speech, Brezhnev declared:

"The Polish Communists with the support of all genuine patriots of Poland will be able, one should suppose, to give a fitting rebuff to the designs of the enemies of the socialist system who are at the same time the enemies of Poland's independence, will be able to uphold the cause of socialism, the genuine interests of the Polish people, the honor and security of their motherland."

Diplomats noted, however, that Brezhnev did not mention "leading party organs" or otherwise extend direct support to Polish Communist Party leader Stanislaw Kania, which they saw as another sign of Soviet dissatisfaction with the former internal security chief who has so far not cracked down on activists in the Solidarity trade union federation as Moscow wants.

These sources were struck that Brezhnev mentioned Cuba right after Poland, pledging "firm support to the country, "an inseparable part of the socialist community." A Soviet official with connections to the ruling Central Committee termed this "a message" to President Reagan, who sent a letter to Brezhnev last week. The Reagan administration has consistently described Cuba as a Soviet "proxy" bent on intervention in the U.S. sphere of influence, and has threatened to take action against Fidel Castro's government.

[Washington Post correspondent Michael Dobbs reported from Warsaw that political analysts there said Brezhnev's speech appeared to be double-edged. It was a qualified expression of confidence in the strength of "patriotic forces in Poland," but it was also a clear message that Moscow still expects action to stem the danger of "counterrevolution."]

The pressure on Warsaw for action is now being applied primarily by Poland's Eastern European allies. Heading a delegation of lower-ranking Soviet officials to the 16th Czechoslovak Party Congress, Brezhnev, 74, made no direct threat of intervention. He did not reiterate what Czechoslovak leader Gustav Husak had stated in a blunt warning opening the session: the Warsaw Pact's right to intervene to preserve communist power in Eastern Europe.

Brezhnev's speech, which he delivered in full to a packed audience in a gleaming new Prague congress hall, is likely to reduce Western worries that Moscow is close to using military force in Poland. The end of the war games, which were unexpectedly prolonged last week when the latest phase of the Polish crisis peaked with threats of a general strike, should further swing concerns away from intervention fears for now.

The games, involving command and control units, began March 17 under Soviet Marshal Viktor Kulikov's direction as Warsaw Pact commander-in-chief, and moved through the Soviet Union, Poland, East Germany and Czechoslovakia. Highly publicized in the bloc, especially in East Germany, the maneuvers were seen as both psychological pressure on the Poles and serious training for possible future intervention.

Analysts here said Brezhnev stopped well short of a firm vote of confidence in Kania's leadership, pointing out that the Soviet president and party chief used the phrase, "one should suppose" in carefully qualifying his view that the Polish party "will be able" to overcome its difficulties.

Brezhnev alluded to the 1968 Soviet invasion of Czechoslovakia, declaring that "the victory over the forces of counterrevolution in 1968 . . . is also a great contribution of the Czech Communists." He pointedly added, "as to the Soviet Union, it was and remains a loyal friend and ally of socialist Poland. On this score, I am sure, we have a common stand with Czechoslovakia as with other countries of the socialist community."

[In Washington, State Department spokesman William Dyess said of Brezhnev's speech, "If he meant to say that the Poles should be allowed to solve their own problems without outside interference, we would wecome this."]

One veteran foreign source here in Moscow said of the speech, "Brezhnev left the low road to Husak yesterday and took a higher route today. But the message remains the same: the Poles have got a pause, but they shouldn't be under any illusions -- the road ahead is full of pitfalls."

Poland's chief delegate to the congress, hard-liner Stefan Olzowski, declared the party "will find enough power and will to take the country out of its social and economic crisis to the road of a stablized socialist development. Nobody will ever succeed in pushing Poland from the socialist road of development.

Brezhnev had nothing more to say about the Polish situation, but if Moscow allows the grassroots political reforms now being launched there to continue unchecked, the result seems certain to alter the nature of the Polish Communist Party by midsummer. The closed, autocratic system of filling ranks would be replaced by one using secret ballots and unlimited candidate slates. It is the sort of model for a more pluralistic brand of socialism which the Soviets have not hesitated to crush in Hungary in 1956 in Czechoslovakia 12 years later.

Washington Post staff writer Dan Morgan reported the following from Berlin:

The conclusion of the Soviet Bloc maneuvers, combined with a Brezhnev speech that was considered moderate in light of recent harsh comments on the Political leaders and news commentors, was greeted with relief in Berlin, a city entirely surrounded by Soviet and East German military forces.

However veteran observers of Eastern Europe pointed out that similar Warsaw Pact staff exercise in Czechoslovakia in July, 1968, had also ended without incident but were followed a month later by a coordinated invasion and occupation of Czechoslovakia.

Western intelligence and military experts have said in the last few days that the maneuvers had increased the readiness of the Warsaw Pact forces for military intervention in the Polish crisis, that the Soviet high command had opted for this solution.