Under pressure from European allies and against the background of lessened fears of Soviet action against Poland, the United States is sounding a goood deal more willing this week than it was a week ago to hold at least preliminary arms talks with the Soviet Union.

Secretary of State Alexander M. Haig Jr. said yesterday that the question of resuming discussion "with a view to us having negotiations" with the Soviets "is under active consideration now and we will have something to announce on this subject in the not-too-distant future."

The Reagan administration swept into office with a double-barrelled blast at the Soviet Union from the president and the secretary of state. From European allies, however, the message for Washington has been that the United States won't be able to base new medium-range nuclear weapons there unless the administration also makes some effort to discuss control of the European-based nuclear arms with Moscow.

In a late-February meeting with Prime Minister Margaret Thatcher of Britain, Reagan stressed that the United States still supports the December 1979 NATO decision to proceed simultaneously along two tracks -- the modernization of nuclear forces in the European theater and nuclear arms control discussions with the Soviets.

Soviet Ambassador Anatoliy Dobrynin visited Haig at the State Department yesterday for an unannounced meeting. It could not be learned whether a resumption of preliminary talks on arms control was discussed.

Although Haig said there would be an announcement in the not-too-distant future, it seemed clear that actual negotiations with the Soviet Union are not close.

First the United States will hold further consultations with its allies and then it will enter what Haig called "preliminary talks with the Soviet representatives with a view to us having negotiations

A State Department official indicated that the process leading up to negotiations might take until early next year.

Haig spoke to reporters yesterday on the south lawn of the White House with NATO Secretary-General Joseph Luns, the first foreign visistor to see President Reagan since he was shot March 30.

Haig, who forged close relations with European leaders during his years as supreme allied commander, has been hearing from all of them that Reagan's apparent early stonewall to negotiations with the Soviets would be likely to make Europeans balk at the modernization of the weapons based on their soil. U.S. defense planners consider these weapons vital.

All questions of U.S.-Soviet relations are being played these days against the back-drop of the crisis in Poland.

After fears 10 days ago that a Soviet invasion or an internal crackdown against the Polish unions was imminent, the Soviet Union ended its military maneuvers nears the Polish border and tension has lessened.

Haig said yesterday the situation in Poland is "considerably improved."

Any Soviet intervention in Poland, State Department officials have said, would make arms control talks with the Soviets impossible.

Defense Secretary Caspar W. Weinberger has gone even further, saying that no talks can be held unless the Soviet Union not only refrains from intervening, but also reduces its military buildup around Poland.