The U.S. ambassador to West Germany, Arthur Burns, has warned in unusually firm terms that anti-American sentiments in Western Europe could lead to a backlash in the United States involving a move to withdraw some American troops from Europe and a return to a sense of U.S. isolationism.

In a speech here last night marking his first major public statement on the subject since arriving in West Germany last summer, Burns, a former Federal Reserve Board chairman, voiced some understanding for the criticism being directed at U.S. policies by a number of West Europeans.

But the ambassador said understanding failed him "when supposedly educated people equate the motives or objectives of the United States vis-a-vis Europe with those of the Soviet Union as many . . . are now doing. That," declared Burns, "reflects sheer ignorance, or intellectual blindness, or perhaps even intentional distortion."

The recent demonstrations in Western Europe protesting what Burns called "the policies that have been the basis of the Atlantic Alliance" had concerned and perplexed Americans, he said. "The people of the United States," he went on, "have been sacrificing materially and personally by maintaining some 350,000 American troops in Europe. . . . They will not stay here if they are not welcome."

Burns called the current European debate about nuclear weapons "a battle for the soul of Europe with clear alternatives," indicating the choice would determine to what extent the United States continued to help defend Europe.

"There may well be a growing sentiment in America to turn back upon itself and let Europe depend for its security and freedom upon its own resources or upon Soviet good will," Burns stated. "Isolationism is by no means the alternative that my country seeks, but many Americans are now wondering whether Europeans are sufficiently mindful of the fact that the Atlantic Alliance has made a free, prosperous and peaceful Western Europe possible during the past 30 years."