Washington boxing promoter James L. Denson, president of the D.C. Chamber of Commerce, is trying to land a prospective heavyweight championship bout between John Tate of Knoxville and Gerrie Coetzee of South Africa for RFK Stadium in September.

Tate's manager, Col. Jerry Miller, said yesterday from Knowville that Denson talked to him about such a promotion on Sunday in Monte Carlo, after they saw Coetzee knock out Leon Spinks in the first round.

Denson was unavailable for comment because he was en route to Washington, but a spokesman for the D.C. Armory Board reported that Denson began negotiations for the use of the stadium before going abroad.

Tate's manager said that he and Coetzee's management must, by terms of their contract, mutually agree upon the site of the projected bout. Miller said he doesn't want to go back to South Africa for another fight.

"We went there once to fight Kallie Knoetze," Miller said. "I don't think we should have to go into the lion's den twice, with 100,000 fans hollering for Coetzee. That would be an inspiration and he's tough to beat, anyhow."

A spokesman for Top Rank Inc., the New York promotion firm, said from San Remo, Italy, that the firm's head, Bob Arum, was trying to book the Tate-Coetzee bout for South Africa with the stipulation that seating be nonsegregated. Otherwise, Arum told reporters, Washington was his alternative choice.

The bout would be for the World Boxing Association title, since the present champion, Muhammad Ali, announced his retirement yesterday from the ring. Larry Holmes is the World boxing Council champion.

In view of Tate's negative attitude about returning to South Africa, his manager was asked how strongly he would insist on the bout with Coetzee being held in Washington.

"I would prefer Knoxville ahead of Washington," he said. "Neyland Stadium seats 80,250 (RFK Stadium seats 52,000). We are setting up a training camp near Knowville. I'm not saying we won't go back to South Africa, but I see no reason why we should be obliged to. The contract we signed before Tate beat (Duane) Bobick and Knoetze in the WBA elimination tournament says the site must be mutually agreed upon.

"I don't want to be argumentative, but we've been there once. We acted in good faith in going there, and so did they (the South African Boxing Board of Control). Arum says there must be integrated seating if the fight is in South Africa, but I'm interested in other things, too."