BRUSSELS, OCT. 3 -- Vice President Bush apologized today for his offhand comment suggesting that Detroit auto workers could use quality-control advice from Soviet mechanics, saying that "I wish I'd never said it, and I'm very, very sorry about it."

Speaking to reporters before leaving for Washington at the conclusion of his 10-day European tour, Bush said, "Well, I thought I was trying to be funny. And, obviously, it didn't work very well."

On Friday, Bush stirred a controversy with a remark after a meeting of NATO ambassadors. He said he had been told about a Soviet military operation involving 350 tanks, none of which had broken down.

Bush said he told the NATO ambassadors, "Hey, when the mechanics who keep those tanks running run out of work in the Soviet Union, send them to Detroit because we could use that kind of ability."

The remark drew immediate protests from Owen Bieber, president of the United Auto Workers union, who called it an "absolute affront to American workers and American ingenuity." Beiber called on Bush to apologize. And the gaffe threatened to worsen Bush's political situation in Michigan, where he has recently suffered setbacks in the delegate-selection process.

Today, Bush apologized without hestitation. "If I offended anybody, I'm very, very sorry because I didn't intend to," he said. "I'm one who has had great respect for the way our automotive people have moved forward in quality.

"One of the reasons we're doing well is because of the quality of our work, and what I was trying to say is, anybody that can keep 350 Soviet tanks going -- that kind of ability is welcome in the United States because quality is our emphasis.

"But look, it's not coming out right, and I didn't like that and certainly if I've offended anybody -- and I understand there's been a little reaction out of the union -- I would apologize and say, hey, give me a break and I didn't mean anything by that."

Bush said he was trying to find "a funny way" to make a serious point about the quality of the Soviet conventional-force superiority in Europe.

"I wish I'd never said it because it's controversial and I have to explain and I'm very, very sorry about it," Bush said.

Campaigning in Manchester, N.H., Bush's major opponent for the 1988 Republican presidential nomination, Sen. Robert J. Dole (R-Kan.), called the Bush comment "unfortunate." Asked if it was an affront to the auto workers union, Dole replied, "I don't want to get into that. Detroit has a lot of quality people. American workers are second to none."

On other topics, Bush said his European swing was certain to help his campaign. Earlier this week, standing in front of his own campaign camera outside 10 Downing Street, the residence of the British prime minister, Bush said the trip had nothing to do with politics. Today, Bush said "I wasn't oblivious" to the camera, "I was just hoping nobody would notice."

Bush also said he thinks that economic sanctions against South Africa "have failed."

His comment was in response to a question about a report President Reagan is sending to Congress on sanctions that were imposed last year. The president opposes the imposition of new sanctions.

However, the vice president did not suggest what should follow the sanctions, saying, "I don't have a clear, easy answer." He urged South African President P.W. Botha to release jailed African National Congress leader Nelson Mandela and open talks with the ANC and others.