Talk by senior U.S. officials about fighting a limited nuclear war, on top of continued squabbling within Washington's foreign policy team, has begun to trouble even leading conservative politicians here, one of whom has warned that the Reagan administration is adding to "uncertainty and disquiet in Europe, above all in Germany."

In a statement, Alois Mertes, in his capacity as foreign policy spokesman for West Germany's opposition Christian Democratic Union, advised Washington to play down public references to military-strategic options and instead focus more on the political character of the East-West conflict. He also urged a stop to the sniping within the administration at Secretary of State Alexander M. Haig Jr., who is seen here as an official who understands Europe.

With crucial U.S.-Soviet negotiations approaching on arms limitations, Mertes said last night that it is important that the United States and Europe follow "a clear and constant course with respect to the Soviet Union."

Implicit in the appeal, which Mertes said represents "a mood that is widely spread" in his traditionally pro-American party, is the feeling that the Reagan administration is not sufficiently attuned to European political sensitivities and may be undercutting its own recent efforts to shore up alliance backing for plans to deploy new medium-range nuclear missiles in Western Europe. The criticism addresses the administration's style, not its policy. The Christian Democrats have not issued a formal statement.

Meanwhile, according to informed sources in London, U.S. Ambassador to Britain John J. Louis Jr. plans to tell the administration during consultations in Washington that there is more to the European peace movement than officials in Washington like to think there is.

Louis is expected to report that conflicting U.S. statements on nuclear strategy fan the movement and add to the concerns of the government of Prime Minister Margaret Thatcher.

Bonn has sought publicly to distance itself from this week's controversy in Washington over nuclear strategy. But Mertes, a leading party figure who was speaking out critically for the first time this year, highlight the seriousness of current U.S.-West German differences and would appear to signal a sort of storm watch in transatlantic relations.

Mertes, who volunteered his comments in a telephone call to The Washington Post here last night, said he was speaking as a friend of the United States and hoped his message would be interpreted in Washington as an attempt "to strengthen the bridge" between West Germany and Washington.

His criticism comes shortly after the Christian Democratic Union's national congress in Hamburg, which had stressed more dialogue with West Germany's youth, many of whom are active in the country's peace movement. There has been controversy in the CDU about how to reconcile the party with the peace campaign and West Germany's now-established detente with the Soviet Union.

Mertes said West Germany's young people "are committed to the values of the West," but are put off by U.S. arguments "framed in military terms." The contrast this week between the military debate in Washington and the youth debate in Hamburg is what Mertes said prompted him to issue his warning.

"The fact that some representatives of the American government overemphasize military-strategic options instead of using more political argumentation, along with the criticism of Secretary of State Haig within the administration, favors the Soviet strategy of raising uncertainty and disquiet in Europe, above all in Germany," Mertes said in a brief formal statement.

"From a European point of view," he continued, "it is important in the current phase for the whole alliance to follow a clear and constant course with respect to the Soviet Union in order to achieve success in the coming arms limitation negotiations, which should lead to a balanced and verifiable reduction in the military potential on both sides without causing a reduction in security."

The U.S. discussion of nuclear plans and options, sparked by President Reagan last month and heated up again this week in congressional testimony by Haig and Defense Secretary Caspar Weinberger, has generally disturbed Europe more than America.

The reason for this has partly to do with Americans being more accustomed to public debate about nuclear weaponry than are West Europeans.

Europeans have been all the more disturbed by what looks to them as the matter-of-fact, almost casual way in which nuclear war is talked about in the United States when it would involve a European battlefield.

Further, there is a suspicious attitude to start with among some segments of the European public toward the security and defense intentions of the Reagan administration.

Mertes, asked what the administration should be saying to win European support for its policies, suggested the following:

The United States should say that the Soviet Union, like the United States, does not not want war and the destruction of Europe. Rather, the Soviet strategy should be described as an attempt to undermine Europe psychologically to get it to follow Moscow's line. In order to do this, the Soviets can be said to be developing a wide range of military options that are intended less for military use than for use as political threats.

This line of argument, Mertes said, is preferable because it frames the East-West conflict more in political than military-strategic terms.

In fact, this line has been reflected in many of the comments made by members of the Reagan administration during the recent stepped-up U.S. campaign -- involving European visits and interviews with European media -- to convey U.S. policy more clearly and convincingly. But much of the American message has tended to be overshadowed here by the references to and controversy over nuclear weapons doctrine.

Haig's comments this week about an allied plan to fire a nuclear "warning shot" and Weinberger's denial of any such concrete plans received prominent play in the West German press. They have not, however, drawn as many sharp political and editorial outbursts as followed the remarks by President Reagan two weeks ago about the possibility of an East-West nuclear exchange limited to Europe.

One of those who joined in the earlier barrage of criticism -- Karsten Voigt, foreign policy spokesman for the parliamentary group of Chancellor Helmut Schmidt's Social Democratic Party -- told the Reuter news service he now felt resigned rather than indignant.

"I think the people who make these remarks must be doing it in the secret hope of strengthening the peace movement," Voigt said sarcastically. "They're certainly succeeding."