An ebullient Mayor Marion Barry called 150 business, labor and civic leaders to a breakfast rally yesterday to promote a title fight between light heavyweight champion Michael Spinks and Eddie Mustafa Muhammad July 15 at the D.C. Armory.

The breakfast was the start of what Barry hopes will be the selling of Washington as "a championship city" to attract boxing matches that he hopes will enhance the city's image and earn money for city government and the tourist industry.

"I've decided that Washington ought to be more aggressive in getting people to see us as more than just a government town. From a business point of view, from a civic pride point of view, I want you to purchase tickets for your employes, or for your union members," Barry said at the 8 a.m. gathering at the D.C. Convention Center. "Buy blocks of tickets. We think this is a legitimate business expense."

As the mayor concluded his remarks, aides circulated among tables distributing sheets of paper on which those in attendance were invited to pledge ticket purchases. Then mayoral aide Joseph P. Yeldell spoke.

"Okay, who's going to buy a big block of tickets? Do I hear 100 tickets?"

There was an awkward silence until parking lot magnate Dominick F. Antonelli Jr. rose. "PMI will buy 100," he said.

Leonard (Bud) Doggett followed within seconds. "Doggett Parking will take 101," he said. Within 90 seconds Yeldell had pledges for 400 tickets from several other contractors and consultants who do business with the city.

The Spinks fight culminates a two-year effort by Barry, an avid boxing fan, to bring a prestigious professional fight to the city. Barry flew at city expense to the Sugar Ray Leonard-Thomas Hearns welterweight title fight in Las Vegas in September, 1981, and also made a trip to Atlantic City last March, when Spinks won a 15-round decision over then-World Boxing Council light heavyweight champion Dwight Braxton. In both cases, Barry said, he lobbied fight promoters to come to Washington.

The fight--dubbed "Duelin' in D.C."--also has on the undercard a match between Braxton and "Irish" Jimmy Smith of Wilkes Barre, Pa. The 10,000 tickets that went on sale this week cost $25, $50 and $100 for ringside.

Barry and Cora Masters Wilds, chairman of the D.C. Boxing and Wrestling Commission, said in interviews yesterday that they vigorously lobbied New York boxing promoter Butch Lewis and pledged him tax breaks and promotional help to get the fight here.

"The mayor never let up," said Lewis. "He was in the ring before the Spinks-Braxton fight in Atlantic City. "I said, 'You're not supposed to be in here,' and he said, 'When are you going to bring a title fight to Washington?' "

The city levies a 6 percent tax on gate receipts, and the boxing commission assesses another 5 percent, which is used to finance operations of the commission, which supervises about a dozen fights a year.

Wilds said that Lewis was already leery of Washington because the city hasn't had a title fight since 1959, when Joe Brown defended his lightweight title with an eight-round knockout of Paolo Rosi at the old Capital Arena. And, she said, the 11 percent tax discouraged Lewis further.

But under emergency legislation passed by the City Council last month, the boxing commission's 5 percent fee will apply only to the first $100,000 of the gate, with the fee reducing to 2 percent on receipts beyond that.

Wilds said she believed the revenue loss to the city was justified because otherwise, Washington might not have gotten the fight.

"We didn't just get a championship fight, we got a quality championship fight," Wilds said.

Barry said that another inducement offered to Lewis was the reduction of the D.C. Armory's customary fee. He said that Barry and other members of the Armory Board agreed to reduce Lewis' cost from more than $25,000 to $12,000.

Most of Lewis' profit on the event will come from television, with the fight carried on Home Box Office and on ABC television several days later. George Krieger, director of sports for HBO, said he expected the bout will draw approximately one-third of HBO's 12 million subscribers. Sugar Ray Leonard will do live commentary on the fight, which is scheduled to be telecast at 10 p.m.

Barry yesterday stressed the importance of having a good turnout at the fight. "I would be awfully embarrassed if we had a live championship fight and had the place empty . . . it will be an embarrassment if the TV cameras pan around the place and those seats are empty," Barry said.

Wilds predicted that if the fight is a sellout, other title bouts will follow. If it flops, industry sources said it is likely to be a long time before a title bout returns to Washington.

Sources estimated Spinks' purse at about $1 million, and $250,000 for the challenger.

"Washington fans are starved for action," Wilds said. In response to a question about whether many city residents would be able or willing to spend $25 to $100 for a ticket, she said boxing is "not just a working class sport. We have ticket requests from everyone, from Tip O'Neill on down."