The Reagan administration, raising the toughness of its language a notch, yesterday called the military takeover in Poland "a matter of the greatest concern" and restricted the movements of Polish diplomats in the United States to the cities where they live.

In parallel statements using almost identical language, the White House and the State Department said the restrictions were being applied in response to similar measures taken Tuesday against American diplomats in Poland.

Last night the White House said that President Reagan has signed a directive establishing a high-level "Special Situation Group" to monitor events in Poland and draw up options. Details on Page A21

Lawrence S. Eagleburger, assistant secretary of state for European affairs, told Polish Ambassador Romuald Spasowski yesterday that the United States is "seriously concerned" about the mass arrests in Poland, including the reported detention of Solidarity union leader Lech Walesa. Such actions, the statements said, are "hard to reconcile with the Polish government's commitment to continuation of the reform process and to political solutions."

The administration's words, while still relatively restrained, appeared to signal a shift from the carefully measured caution, which had characterized all U.S. statements since the weekend crackdown, to addressing Polish and Soviet authorities in noticeably blunter terms.

To underscore that point, U.S. officials said, Reagan is likely to open his news conference today with a statement stressing the seriousness with which the United States regards the Polish crisis. The officials said the advisability of the president speaking out publicly was among the topics discussed late yesterday at a White House meeting of Reagan's Special Situation Group, which is chaired by Vice President Bush.

In addition, administration officials privately laid increasing stress on the contention that the imposition of martial law led by Polish Gen. Wojciech Jaruzelski was not simply a nationalistically inspired act aimed at extremist dissidents but was more likely the result of Soviet pressures and behind-the-scenes direction from Moscow.

This attitude, which has become increasingly apparent among U.S. officials during the past two days, seemed to be placing the United States at odds with America's West European allies, who have tended in their public utterances to treat the situation as an internal Polish power struggle.

So far, most senior U.S. officials have been very circumspect about stating this view openly. When State Department spokesman Dean Fischer was asked yesterday about the Soviet role in Poland, he said only that there is no evidence of overt Soviet intervention.

But White House communications director David Gergen, answering a similar question, said, "It is clear that Soviet pressure very likely contributed to the Polish decisions."

The administration also became bolder yesterday in talking about the specific economic weapons it might bring into play if the Polish situation builds into a major confrontation between Washington and Moscow. Agriculture Secretary John R. Block, who fought successfully to end the U.S. grain embargo against the Soviet Union, told a Senate subcommittee that any new sanctions that might be imposed as the result of the Polish crisis would cover the full range of U.S.-Soviet trade.

Lawrence Brady, assistant secretary of commerce for trade administration, was even more explicit in an interview with the Newhouse newspapers. He said that Soviet intervention in Poland would mean a new grain embargo and a U.S. effort to convince the West Europeans to cooperate in halting high-technology exports to the Soviets and withdrawing their cooperation from construction of a pipeline to bring natural gas from Siberia to the West. All of these eddying currents appeared to make yesterday's statements by the administration the first salvo in what could be an escalating campaign to put the Soviets on notice that they will pay a high economic price if the repression in Poland continues.

As White House deputy press spokesman Larry Speakes said: "We are delivering these thoughts, and I think they are well understood by Poland and others."

Fischer, speaking for the State Department, said: "The situation . . . continues to be a matter of the greatest concern . . . . We have made our views known to Polish authorities and to the government of the Soviet Union. Soviet military intervention in Poland would have a severe and lasting effect on East-West relations."

He added that Spasowski, who was at the department for the fourth consecutive day, had been informed that reports about Walesa not being "a free agent" and the arrest of other dissidents were contrary to the Polish government's stated commitment to reform and its adherence to the 1975 Helsinki Final Act, which calls for respecting civil liberties in signatory nations.

Fischer also said the United States had protested "in the most vigorous terms" the restrictions placed on American diplomats in Poland and the posting of police outside U.S. consulates in Warsaw, Krakow and Poznan.