Arthur Ashe, captain of the U.S. Davis Cup tennis team for the past five years, announced his resignation yesterday, less than 24 hours after published reports indicated he had been told his contract would not be renewed. Former top players Stan Smith, Marty Riessen and Brian Gottfried are the leading candidates to replace Ashe, sources said yesterday.

A new captain will be selected next week, said J. Randolph Gregson, president of the U.S. Tennis Association, in a telephone interview from Scottsdale, Ariz., where the USTA management committee is meeting and considering a consultant's study to streamline the organization.

"There is no front-runner" to replace Ashe, he said.

In a statement released by the ProServ agency here, Ashe said that he had talked several weeks ago to Gregson and Gordon Jorgensen, USTA vice president and chairman of the Davis Cup committee, and told them that if they felt a change was necessary, he would step down. Ashe called his resignation "in the best interests of me personally and of the team."

Although USTA officials have said Ashe's health -- he has had a heart attack and two bypass operations -- was a factor in his resignation, Ashe said in a telephone interview that it wasn't. "It hasn't interfered in my Davis Cup captaincy," he said.

Gregson said that Ashe, 42, a former U.S. and Wimbledon champion who has been involved in Davis Cup more than half his life, will remain in the USTA hierarchy, as vice chairman of the Davis Cup committee.

In his statement, Ashe said the toughest part of being captain was not always having the best U.S. players available.

Both John McEnroe and Jimmy Connors, the top two men's players in the United States this year, declined to play on the 1985 Davis Cup team after USTA officials asked them to sign a code of conduct. According to Ashe and Gregson, players will not be asked to sign the guidelines in 1986, but only agree to abide by them.

Connors said earlier this year that he never would play Davis Cup again; Ashe said that McEnroe is eager to resume Davis Cup competition, but only in singles. A USTA official who asked to remain anonymous said Gregson would enforce the code if players broke it and, therefore, the USTA president feels no signature is necessary.

Gregson evaded commenting about a report in yesterday's editions of the New York Times that quoted sources as saying Ashe "reportedly has fallen out of favor with . . . Gregson for a perceived lack of discipline and organization on the team."

Asked if that were accurate, Gregson said, "I don't care to comment. It's not apropos." Asked if Ashe was fired, Gregson said, "He resigned . . . There was no gun to his head."

The United States won the Davis Cup during Ashe's first two years as captain. But the United States has lost each of the last three years on slow clay courts in South America and Europe, including early-round losses to Argentina in 1983 and to West Germany this year. Ashe's overall match record was 13-3, and among captains in the last four decades, only Billy Talbert has served longer (six years).

Gregson compared the decision to a change of leadership in any business. "Anytime there's a change you want a better program, and you think somebody else can give it a better go. But with somebody with Arthur's stature, to say he was fired because he didn't win -- that's certainly not the case here."

Gregson said that he will meet with Smith, Riessen, Gottfried and Dick Stockton, another top former player, "in the next day or two out here" and that he and Jorgensen will decide on the new captain next week.

Gregson also said Tom Gorman, captain of the U.S. Wightman Cup team, will be interviewed next week in Williamsburg, Va.

"I've got an open mind," he said.

Gregson also said the USTA is beginning a search for an executive director "with far-reaching powers . . . to deal with the complexities of tennis as it is now." Currently the USTA is led by a president who serves a two-year term. "You can't bring in someone from New Orleans to run it for two years and then bring in somebody from Phoenix or Hartford for two more," Gregson said.

That was the major recommendation in the study by McKinsey and Co. "It's not revolutionary, but it will pull us into the 19th century -- maybe not the 20th century but out of the Dark Ages," Gregson said.