President Carter quietly but so far vainly signaled the Soviet Union in the early stages of the Polish workers' strikes that Moscow must show progress in human rights or face an intensified diplomatic attack from the United States.

That attack is now planned for the late-fall meeting in Madrid of the United States, Canada and 33 Europeans countries, including the Soviet Union, that signed the 1975 Helsinki agreements promising to uphold human rights. It gives Carter the best of two worlds: a chance to make political gains in his campaign against Ronald Reagan among large and potent ethnic groups, and a change to show anti-Soviet muscle at a time when Moscow is under attack around the world for its invasion of Afghanistan.

Although the strike by Polish shipyard workers was triggered by economic issues, mainly inflation and meat subsidies, it is fast taking on a hard political coloration: the lack of political freedoms in communist Poland caused by the iron hand of Moscow.

If the workers' strike, now centered in the shipyards of Gdansk, leads to arrests, trials and new political repression -- a 50-50 possibility as viewed by top Carter administration officials -- Carter's envoys will go to the Madrid "helsinki review" conference with potent new ammunition to use against Moscow.

As yet, there has not been the slightest response from the Kremlin to Carter's appeal for some demonstration of human rights concessions in the Soviet Union and its Eastern European satellites in this pre-Madrid period. The warning signal was sent by Secretary of State Edmund Muskie in an unreported talk he had the morning of July 31 with Jewish, East European and other ethnic leaders called into the State Department.

Warning of a tough American offensive at Madrid, Muskie said the United States would take "positive account of any significant progress on human rights" by Moscow before the Madrid meeting begins.

Those words were telegraphed on Carter's orders to all American ambassadors abroad for transmission to their counterparts to show the trend of Carter's thinking. Carter himself told the same ethnic leaders later that day in the White House that Moscow had "dishonored the principles of the Helsinki accords, both inside and outise its own borders" and praised the "courageous men and women how in prison or exile" for seeking enforcement of human rights.

When Poland's communist government forcibly repressed the last wave of workers' revolts in 1976, illegal Workers Self-Defense Committees were formed that still operate in a Polish political climate measurably freer than that inside the Soviet Union. Reports spirited out of Poland by these human rights committees were used to bolster the human rights attack against the Soviet bloc led by the United States in the 1975 "Helsinki review" conference in Belgrade.

Failure of the Polish communist regime to settle the new and rising demands of workers without repression could produce far more evidence of human rights violations for the United States to brandish at Madrid. Carter intends to use it not only to put Moscow on the spot but to strengthen the U.S. position with Western allies who, despite Afghanistan, are fearful of antagonizing the Soviets at Madrid.

With the U.S. election 10 weeks off, there is no reluctance here to make political capital out of the human rights issue. As one White House aide told us: "Did you notice that the best spontaneous applause Carter got in his acceptance speech was when he trumpted human rights?"

Max Kampelman, the defense-oriented Democrat who will be co-chairman of the U.S. delegation in Madrid, discovered that most European statesmen did not particularly like his message when Carter sent him to brief them on the hardline U.S. stance being prepared for Madrid. But when Kampelman took the president's message to seven major U.S. cities recently in quiet talks with Jewish and East European ethnic leaders, his pledge that Carter would pull no punches at Madrid was emotionally applauded. Their only question: does Carter really mean it?

Carter's aides say he does. What is happening today in the Baltic ports of Poland plays into his hand, dramatizing his repeated appeals for Western solidarity to contain Soviet power and enhancing his standing at home.