Muhammad Ali gave a clinic yesterday for Mike Weaver, the new World Boxing Association heavyweight champion.

At a news conference in Los Angeles at which he was expected to announce he was going to fight Weaver, Ali announced instead that he was going to fight World Boxing Council champion Larry Holmes July 11 in Rio De Janeiro.

The unpredictable Ali explained on the telephone from his home in Los Angeles: "Bob Arum and Murad Muhammad had differences about terms, so Murad and Don King are going to promote the bout. I wanted Holmes . . . I finally got him."

Murad Muhammad, 29, is a new figure on the promotional scene who used to be a member of Ali's entourage. He has staged bouts in Newark, N.J., as president of Prime Sports, including five in Rahway (N.J.) State Prison, featuring inmate James Scott, a light heavyweight.

Arum is head of Top Rank Inc., a New York City promotional firm. He staged the fight in Knoxville, Tenn., March 31, in which Weaver won the WBA title from John Tate. New York promoter King has staged all of Holmes' championship fights.

Don Manuel, Weaver's manager, said from his Los Angeles home: "I was surprised by Ali's announcement; everybody is surprised. Arum had an option on Weaver's next three fights and he told me he had Ali under contract, too.

"Weaver and I were invited to the news conference today, but we didn't go because Murad didn't come up with $100,000 in front money we were promised. We were supposed to receive $2 million-plus to fight Ali. I talked to Arum yesterday (Tuesday) and he said everything was fine."

"It's good that Weaver and I didn't go to the press conference. We would have been embarrassed. We all fel bad, but I'm glad for Ali to be making the money (believed to be $6.5 million).

"I'll believe the Ali-Holmes fight is on when they start selling tickets. Ali got $100,000 in front money and is supposed to get another $150,000.

"We got nothing, because we didn't want $100,000 up front unless we got an agreement for the fight with it that said the $100,000 was not refundable if the fight didn't come off.

"Fifteen minutes before the press conference ABC television people came to my place to do an interview with Weaver, and were asking questions when we got the news that Holmes got the bout. I don't think Arum knew. He had been in Panama working on the Sugar Ray Leonard-Roberto Duran bout. I didn't know, but I was getting suspicious when we didn't get our upfront money or an agreement from Murad.

"We would have liked to fight Ali and made the money, but Mike is still WBA champ and will defend his title no later than July."

Ali was asked about spurning Weaver and said, "I don't care about Weaver now. I'll beat Holmes to become the quardruple champion and then I'll beat Weaver to be the quintuple champion. Holmes is the best in the world -- next to myself, of course. I can whup him. He's old, he's 31." t

Ali, 38, said of Arum being dealt out of the promotional picture: "He wanted all of it -- the television rights the foreign rights, everything."

Promoter Murad Muhammad said, "The agreement with Weaver was acceptable, but the agreement with Arum was unacceptable. The arrangements weren't acceptable to investors (in Brazil)."

Holmes said in Easton, Pa., "I gave my agreement at 3 a.m. this morning (Wednesday). I asked for $4 million and they mentioned $3 million to $5 million. I'm sure a figure can be agreed upon. I'm supposed to get $200,000 on Tuesday; then I'll sign."

Holmes, a onetime sparring partner of Ali, said that after he beats Ali he wants to fight Weaver in the autumn to unify the title.

Last week, Bob Martin, the Las Vegas oddsmaker, said Holmes would be such a favorite over Ali if they fought that there probably would be only "sympathy bets on the three-time champion. He won't win a round from Holmes."

When that was mentioned to Ali yesterday, Ali said, "That's why I want to fight Holmes. I have always beat the ones the people said were unbeatable -- Sonny Liston, George Foreman, Joe Frazier the second and Third times I fought him, and Ken Norton after he broke my jaw."