The Reagan inaugural committee yesterday did an about-face and announced that it would pay 200 performers triple the minimum union wage for singing, dancing and other work done during inauguration week instead of having them perform free, as had been planned.

The change in plans was lauded by labor union officials who had called the proposal "an insult" and promised to picket inaugural performances if union wages were not paid. It appeared to end a bitter, week-long feud between the inaugural committee and organized labor.

"They were just completely off the mark on this one, and they knew it," said Al Eisenberg, executive secretary of the Actors Equity Association.

Under terms of the new agreement, the inaugural committee will pay singers and dancers $375 for four days' work, plus travel and living expenses as well as contributions for each performer to the pension and welfare fund of the American Guild of Variety Artists.

The feud began early last week when an ad placed by the inaugural's producer appeared in a trade publication calling for 200 non-union, "clean-cut all-American types" to perform free during the inauguration festivities. Labor unions, including the Screen Actors Guild once headed by President Reagan, found the "clean-cut" clause offensive and demanded that wages be paid.

Inaugural spokesmen apologized for the ad's language, which was blamed on inaugural producer Robert Jani, but held firm on no pay. They dismissed union protests as a misunderstanding of the role of young amateur performers in inaugural celebrations and said they'd only placed the advertisement to alert college and high school students to the opportunity.

Union officials attributed yesterday's agreement, which was signed by Jani and the Actors and Artists of America, an umbrella group of four entertainment unions, to several factors including the long arm of the president himself.

"We asked the president to reverse this decision on grounds that to do so would be a marvelous symbol, a public demonstration of the idea of the dignity of the artist," said Equity's Eisenberg.

"I can't read their minds, but I think that they realized this was more than just a union complaining," said Sanford Wolff, national executive secretary of the American Federation of Television and Radio Artists, one of several entertainment unions to protest the entertainment. "They realized that they had offended a rather large segment of the American public." Late last week, Wolff filed a formal complaint with the U.S. Department of Labor protesting the no-pay plan.

John Buckley, an inaugural spokesman, said yesterday that neither the president nor committee officials were involved in the initial decision to use unpaid labor, or in its reversal. He attributed both problem and solution to Los Angeles-based producer Jani.

Buckley last week said the committee's budget of $12 million was not enough to pay 200 performers the U.S. minimum wage of $3.35 an hour.

Buckley declined to estimate how much the change would cost, but said the difference would come out of producer Jani's pocket and not out of inauguration coffers. "Whatever the costs, it's not the inaugural committee that's going to pay," Buckley said.

Buckley described Jani as the "best producer in the business," the man who produced the opening extravaganza for the Los Angeles Summer Olympics, the Tall Ships ceremonies for the Bicentennial as well as the half-time ceremony of last year's Super Bowl. "He got this job because he is the very best in the business," Buckley said.

Jani could not be reached for comment, and Buckley would not speculate on his reasons for making the switch. Union leaders applauded it, nonetheless.

"If they're working as performers, they should be paid. It's nonsense to say they're amateurs, or they're doing it for the privilege," Eisenberg said. "It's always a privilege to work for nothing."