In his quest to nurture fresh unity in the Atlantic Alliance, President Reagan has embraced West German Chancellor Helmut Kohl as a conservative soul mate whose election next March is deemed crucial by the White House to build a more compatible coalition among its European partners.

During his two-day visit here this week, Kohl offered repeated assurances about Bonn's faith in Washington's allied leadership. In a speech Tuesday to the American Council on Germany in New York, Kohl stressed that "we want to talk with you, and not about you."

His comment was a pointed allusion to the hectoring style of Helmut Schmidt, who carped frequently about U.S. indecisiveness before he was toppled by Kohl in a no-confidence vote Oct. 1.

But while Kohl was happy to reciprocate Reagan's effusive tidings, he also conveyed a discreet plea that a more conciliatory U.S. approach to the Soviet Union would make political life a lot easier for the administration's friends in Europe. Now that Schmidt has renounced plans to run again for chancellor, the Reagan administration sees the prospect of a Kohl victory in elections next March as an opportunity to reinforce a conservative axis in Bonn, London and Washington.

With Socialist French President Francois Mitterrand looming as an increasingly prickly partner, Washington believes that a stronger alignment of conservative governments could prove vital in coping with sensitive alliance disputes.

The recent imbroglio over Reagan's decision to lift sanctions in the trans-Siberian pipeline controversy aggravated Washington's relations with Paris and seems to have underscored the view that Reagan's most natural ideological allies are Kohl and Britain's Prime Minister Margaret Thatcher.

Reagan declared last week that "substantial agreement" among the allies on an East-West trade strategy enabled him to drop sanctions against firms involved in building the Soviet natural-gas pipeline. While most of the allies hailed the move, France brusquely claimed it was "not a party to the agreement."

U.S officials have admitted that the announcement of the decision was timed partly to eliminate an irritant before Kohl arrived and to provide a more harmonious atmosphere for their talks.

Kohl's Christian Democrats anxiously hope the administration will tone down its anti-Soviet rhetoric and achieve progress in arms control talks so that their fortunes at the polls will not suffer from a possible resurgence of the peace movement.

Seeking to use their amicable relations to influence administration behavior, Kohl and his top advisers have encouraged the White House to adopt a more temperate course in dealing with the Soviets that might produce a more sanguine political climate in Europe.

In his talks with Reagan and in his New York speech, Kohl said he favored a "well-timed and well-prepared" summit between the U.S. president and the new Soviet leader, Yuri Andropov, and suggested that such a meeting would be enthusiastically welcomed in Europe.

In Washington last week, West German Defense Minister Manfred Woerner said he was greatly pleased by assurances from Vice President Bush that the administration adamantly rejected the notion of fighting a limited nuclear war in Europe.

Earlier comments by U.S. defense officials about "winning" a nuclear war aroused fears about Europe becoming a sacrificial battleground for the superpowers.

While administration officials remain uncommitted to the idea of a U.S.-Soviet summit, Reagan appears eager to do all he can to assist Kohl to win a mandate at the polls.

"The Germans are so important to just about everything we do," explained a State Department official. "It is in our interests to work with the most stable of all possible West German governments, and that now is in the direction of the Christian Democrats."

Administration officials said that Reagan finds strong affinities in Kohl and Thatcher because he met them while out of power and they later gained power by defeating center-left politicians.

Despite Reagan's clear preference to deal with Kohl, Bonn's government is not expected to introduce major policy changes, even after the March elections, that might be interpreted as a strong shift to conservative orthodoxy. "There have been really no great changes, only small nuances, in government policies since Schmidt left office," admitted a State Department official.