Secretary of State George P. Shultz tonight called Berlin a symbol of the "unnatural and inhuman" division of Europe and said the United States does "not accept incorporation of Eastern Europe, including East Germany and East Berlin, into a Soviet sphere of influence."

In a speech to a Berlin journalists' society prepared for delivery here, Shultz, who on Sunday begins a trip to three East European countries, said the Soviet Union for 40 years has forced the people of Eastern Europe "to live in a continent divided by barbed wire, under governments sustained by military power."

Before delivering his address, Shultz, wearing a workman's cloth cap to protect himself from pelting rain, visited the Berlin Wall accompanied by West German Foreign Minister Hans-Dietrich Genscher and West Berlin's governing mayor Eberhard Diepgen.

He said the U.S. search for better relations with Moscow has not caused President Reagan to forget "that there can be no true peace where there is repression, partition or mutual fear, or where we avert our eyes from unpleasant facts."

Instead, he said, the postwar history of West Berlin, a western enclave 120 miles inside the communist east, is a reminder that "guns and tanks and rockets are a manifestion of basic differences, not the underlying cause.

"There isn't a Berlin Wall because there are weapons; there is a military confrontation because of a political system that is so dependent on force that it builds a Berlin Wall. This is why President Reagan has sought to place U.S.-Soviet arms-control issues in their political context," Shultz said.

His tough rhetoric, tinged with tones reminiscent of the Cold War, was in the style set by President John F. Kennedy in his "Ich bin ein Berliner" speech here in 1963.

It appeared to be a signal of the impression he wants to leave in Eastern Europe. There he will visit Romania and Hungary, two Soviet bloc countries that have sought a cautious degree of independence from Moscow, and Yugoslavia, an independent communist state.

The message, U.S. officials said, is that the United States and its allies will not make agreements with the Soviet Union under the threat of force. Nor will they allow any agreements to cause the West to abandon its policies of human rights, noninterference in other countries and greater freedom of movement between the two parts of Europe.

"Berliners know that the Soviets will push for advantage when they think they see weakness and indecision," Shultz said, recalling how the West stood firm against Soviet pressure during the 1948 Berlin airlift and the other crises that have beset this city in the past 40 years.

He said the same lesson was evident in western reaction to Soviet threats against the deployment of U.S. medium-range missiles in Western Europe.

"We were not frightened when the Soviets walked out of the Geneva arms-control talks in December 1983 and said they would never talk once our missiles were deployed," he recalled. "The alliance held fast, and the Soviets returned to the bargaining table in 1985."

Then, he continued, the Soviets said they would not discuss reduction of strategic or medium-range missiles in the present Geneva arms talks until the United States agreed to renounce its Strategic Defense Initiative.

"This, President Reagan has made abundantly clear, we will not do," Shultz said. "Well, again our firmness has produced results. Just over two months ago, the Soviets made a counterproposal . . . and at the president's meeting with Soviet leader Mikhail Gorbachev in Geneva, new impetus was given to the negotiations.

"Progress, in the future, as in the past, depends vitally on western unity and perseverance."

Shultz recalled that when Reagan visited here in 1982, "he called upon the Soviet Union to join him in fulfilling the hopes for unity, peace and prosperity represented in this city . . . . Sadly, in 1982, the Soviet Union seemed unable to respond to the president's vision.

"Perhaps there is greater hope today," Shultz said. "We know the limits as well as the possibilities of summit meetings. Yet we believe the continued face-to-face dialogue of our top leaders could help us move forward.

"It is worthwhile for the new Soviet leadership to see our resolve firsthand. The world can only be better off if these men see that the democracies will stand firm against pressures and also that we are ready to deal with them constructively across the range of our differences.

"We will not be bullied, but we are ready for give-and-take in negotiations and for fair solutions to the problems that divide us. These are the lessons that we have all learned from the brave people of Berlin."

Before flying here late this afternoon, Shultz lunched with West German Chancellor Helmut Kohl at Kohl's home near Ludwigshafen. Kohl's coalition government is embroiled in a dispute about whether West Germany should participate in SDI research.

Later, during the flight to Berlin, Shultz told reporters that Kohl had advised him that the Bonn cabinet will decide the issue Wednesday, the day Shultz is scheduled to return Washington. He quoted Kohl as saying, "By the time you land, we will have made our decision.