Secretary of State Edmund S. Muskie, speaking as the son of an immigrant from Russian-occupied Poland as well as the senior U.S. diplomat, strongly attacked the French Olympic Committee today for an "incomprehensible" decision to attend the Moscow summer Games despite the Soviet invasion of Afghanistan.

Muskie's strong appeal for allied support on the Olympic boycott -- and on economic sanctions against Iran -- came as the North Atlantic Treaty Organization pledged to strengthen the Western military alliance in response to the Soviet move into Afghanistan.

Vowing to bolster NATO forces, the meeting also took under study an unexpected Dutch proposal to set up a second NATO naval squadron to replace U.S. warships diverted from the Mediterranean Sea to the Persian Gulf.

Muskie, in a sidewalk interview following a round of meetings with European leaders, expressed "deep concern" that failure of the Olympic boycott could undermine U.S. and allied efforts to show the Soviets that armed invasion is unproductive.

For representatives of free nations to march into the stadium at Moscow "with our young people embracing Moscow," said Muskie, would be taken by the Soviets as "confirmation of the rightness of their foreign policy . . . their system, their aggression in Afghanistan."

He said he spoke "not so much as secretary of state as a citizen of the U.S. whose father was born in Russian-occupied Poland in the last century."

Muskie's strong comments on the French decision and a two-hour meeting with West German Foreign Minister Hans-Dietrich Genscher were part of a sudden drive by American officials to prevent the Olympic boycott movement from disintegrating in the wake of the French Olympic Committee decision Tuesday to attend the Moscow Games.

The West German committee is scheduled to make its decision Thursday in Dusseldorf. U.S. officials called this the "critical" decision. The deadline for national committee actions is 10 days away.

Genscher, according to informed West German sources said he was "hopeful" that his countrymen will back up the government's strong recommendation for a boycott of the games. But the outcome, by both U.S. and German accounts, is uncertain.

The European states, in the NATO meeting's communique, endorsed what has been the U.S. view of the Afghanistan invasion all along -- that changed the international strategic balance and a posed a threat to Western security. Initially, many European countries saw the Soviet move largely as a defensive action along Moscow's border, with only peripheral bearing on East-West relations.

For the first time in the postwar era, the Soviet Union had used military force to impose its will on a nonaligned country of the Third World and in a way which affected the overall strategic situation," the NATO communique said. It went on to say that the ministers denounced this use of force and called for "total and immediate withdrawal of all Soviet forces from Afghanistan."

This was the first such NATO ministerial session since the Soviet invasion of Afghanistan last December. The final communique was particularly important for the unambiguous recognition it gave to NATO's authority and need to respond to events outside the boundaries of Europe.

U.S. officials went to unusal lengths today to say that President Carter's concern about the invasion goes well beyond partisan political purposes. A senior official told reporters that Carter's plans for economic measures and the Olympic boycott against Moscow are the "minimum response" demanded by the U.S. Congress and public.

Beyond attendance at the formal meeting the NATO alliance, Muskie spent much time and energy in his first round of international negotiations on shoring up European sanctions against Iran.

Several nations, especially Britian and France, are reported to be planning to water down the sweeping anti-Iran sanctions adopted April 22 by nine European allies. Muskie is attempting to convince the allies to stand firm behind the original decision.

Muskie made explicit his view that "I don't see any military option that promises or guarantees success" in obtaining release of the hostages. He suggested reliance instead on the kind of economic pressure that the European sanctions represent.

"Pain is a highly motivating force . . . in our private lives and in the lives of nations -- and it seems to me that (economic) sanctions are a very specific way of communicating to Iran the shape of the economic future with which they must deal.

"I don't know how you can find a way to more directly influence their conception of that fact than to use the sanction route. I would hope that our European friends would understand that," Muskie said.

Despite what was described by U.S. diplomats as a powerful presentation by the new secretary of state, it seemed that the extent of the European sanctions against Iran was uncertain at the end of Muskie's meetings here tonight.

The European decision on the sanctions is scheduled to be decided and announced Saturday in Naples.

Gierek spoke at the opening session of a two-day meeting of the seven-member Communist Warsaw Pact, which was formed exactly 25 years ago at the height of the Cold War as a counterpart to NATO.

The session was attended by Soviet President Leonid Brezhnev and a powerful Kremlin delegation.

Gierek said detente was "dangerously overshadowed by the intensified activities of imperialist and Cold War forces." These forces, he added without naming NATO directly, were seeking to upset a military balance and pursue policies from a position of strength.

In Moscow the influential newspaper Literaturnaya Gazeta attacked what it called West Germany's growing militarism. It said the Bonn government had taken upon itself the "lion's share" in building up Western military efforts in Europe and was virtually claiming military predominance in Western Europe.