President Reagan, who arrived here today on the eve of a seven-nation economic summit meeting, reaffirmed his commitment to make a controversial visit to a German military cemetery but quickly shifted the focus of international attention by announcing here that he was imposing trade sanctions against Nicaragua.

Reagan and the leaders of the five other major western industrial nations and Japan gathered here today for an annual economic summit that begins Thursday evening. It will focus, as in the past, on international trade issues. But unlike previous summits, this year's meeting was also meant to celebrate the 40 years of reconciliation with postwar West Germany since the end of World War II in Europe.

But the effort has been overshadowed by Reagan's plan to visit a military cemetery where Nazi SS troops are buried. Today, White House spokesman Larry Speakes announced that the West German and U.S. governments had decided not to add to the president's schedule a stop at the site of the Remagen Bridge across the Rhine suggested by Jewish groups in the United States that had objected to the visit to Bitburg cemetery.

Many Jewish groups and veterans' organizations strenuously have opposed the Bitburg stop, and a visit to the site of Remagen Bridge was seen as a way to honor U.S. World War II soldiers.

The furor in the United States over the visit to the cemetery intensified when it was learned that 49 members of Adolf Hitler's SS units are buried there along with about 2,000 other German soldiers. The controversy in the United States set off a sharp reaction here with many West Germans offended by the criticism of what they saw as a necessary gesture of reconciliation.

There were further indications today that the White House was still trying to defuse the controversy.

In an interview with NBC-TV here, White House chief of staff Donald T. Regan predicted that "by the time the whole of Sunday is over, all of the things that we do on Sunday are put in perspective, the world will see Ronald Reagan in a different light."

The summit ends here on Saturday, and on Sunday the president, accompanied by West German Chancellor Helmut Kohl, will visit the former Nazi concentration camp of Bergen-Belsen first to pay homage to the victims of the Nazis and then go to the Bitburg cemetery for a symbolic, 15-minute wreath-laying ceremony. Then the two leaders will have lunch with U.S. and West German troops at the big military base at Bitburg.

Speakes told reporters here that Reagan's first action upon landing here early this morning was to order a trade embargo and other economic sanctions against Nicaragua. But Speakes disputed suggestions that using Bonn as a platform for such an announcement was part of the effort to defuse the Bitburg controversy or was designed to dominate the news on a day in which Reagan had no other publicly scheduled activities.

When a reporter asked today whether it would be "too cynical to suggest you timed this move in the middle of Europe to take the heat off the president's trip to Bitburg," Speakes responded, "Yes, it would."

But the controversial visit continued to pop up beyond the control of the White House.

West Germany's biggest circulation newspaper, the racy tabloid Bild, said it would publish an article Thursday reporting that Gymnich Castle, the official guest house where Reagan is staying, is owned by a godson of Hitler.

It was the kind of report that White House officials would normally brush off. But they appeared to be annoyed by it today as they sought to dampen the Bitburg controversy.

In the television interview, chief of staff Regan indicated that the president is less than enthusiastic about the Bitburg visit.

"I think the people understand that here's a man torn between what has to be done for state reasons and what he would like to do for personal reasons," Regan said.

"Since we're guests here, we're doing as our hosts have asked us to do," he said.

Regan insisted that the president "is not blurring the Holocaust at all" and will reiterate during the visit to Bergen-Belsen that "genocide is something that we simply cannot tolerate, will not tolerate."

The Bild newspaper report said the guest house is owned by Baron Joerg von Holzschuher, a godson of Hitler. The baron was quoted as saying his father was a good friend of Hitler but turned against the Nazis before the end of the war.

"I think it was wrong to write about this now in connection with the high sensitivity of the president's visit to Bitburg," the newspaper quoted the baron as saying.

The 700-year-old castle, the official guest house of the German government, is surrounded by a deep moat in the middle of a park 25 miles from here.

Asked about the report, Speakes said, "It's a government guest house; I think every high government official stays there."

After a day's rest at Gymnich Castle today, the president will meet Chancellor Helmut Kohl Thursday for a morning round of talks, followed by sessions with Japanese Prime Minister Yasuhiro Nakasone and British Prime Minister Margaret Thatcher, in a meeting arranged in the last few days. The meeting with Kohl will be the first between them since the flap over Bitburg erupted and added some strains to what had been excellent relations between the president and the chancellor and their respective staffs.

Nakasone joined Kohl today in supporting the Reagan administration's call for a new round of international trade liberalization talks by early next year. The Japanese prime minister, who has been under intensifying pressure from the West to open his country's markets, told reporters at a joint news conference with Kohl, "We want to fight the growing tendency toward protectionism."

A Japanese spokesman later quoted Nakasone as telling Kohl in their two-hour meeting, "You can rest assured that the Japanese economy will become more open than it used to be." And the White House announced agreement with Japan to expand air passenger and cargo traffic.

The statement came as Reagan faced possible hurdles to winning agreement from France and Italy to open trade talks early next year. President Francois Mitterrand and Prime Minister Bettino Craxi have urged this week that a new round of trade talks should be linked to international monetary reform.

Kohl has made it clear he wants to avoid conflict over sensitive political issues, including Reagan's proposed Strategic Defense Initiative. West German officials said a single political declaration, emphasizing the theme of peace and reconciliation among the allies, is Kohl's primary objective for the three-day summit.

Nakasone and Kohl today renewed their support for the research phase of the Strategic Defense Initiative, but said they want any plans for deployment to be subject to negotiations with the Soviet Union.

After a 7 1/2-hour flight from Washington, Reagan arrived at the Cologne-Bonn Airport under gray skies and rain that stopped just before he disembarked. He was greeted by Foreign Minister Hans-Dietrich Genscher and his wife along with 200 spectators waving West German flags. A squadron of four Tornado military jets swooped low in a welcoming salute.

Minutes before he arrived, police defused a bomb in Bonn's diplomatic quarter, at an aerospace industry office. Police said it was a fire extinguisher filled with 13 pounds of explosives. No group claimed responsibility. Police have feared leftist terrorist attacks during the summit.

Budget problems in Washington followed Reagan to Bonn. The White House sought to put the best face on a narrow 50-49 victory in the Senate for its budget compromise. "The budget is very much alive in the Senate," Speakes said.