Boston Celtic forward Cedric Maxwell was fined $2,500 by the National Basketball Association today for charging into the stands after a heckler during the sixth game of the Eastern Conference championship playoff series last Friday at the Spectrum in Philadelphia.

In announcing the fine, NBA Commissioner Larry O'Brien said in a statement: "Regardless of the provocation, players must avoid confrontations with the fans in the stands, and any player engaging in similar conduct in the future will face even more severe penalties."

Maxwell said he was sorry for the incident and chose not to comment further. Matt Winick, the NBA's director of media information, said O'Brien would have no further comment on the incident or the fine.

The fine is considered stiff by NBA standards. When Washington Bullet Kevin Grevey bumped an official in a game midway through his past season, he was fined $1,000 and suspended for one game. Kermit Washington, then with the Los Angeles Lakers, was fined $10,000 and suspended 60 days in 1977-78 for throwing a punch at Rudy Tomjanovich of the Rockets. That is the stiffest fine imposed for fighting in league history.

If the Celtics were not involved in the league finals, Maxwell most likely would have been suspended as well as fined, according to one league official.

The incident occurred when Maxwell's momentum carried him off the court and into the seats in trying to stop a 76er basket. He was called for a foul on the play. As Maxwell was walking back to the court, 55-year-old Ray Kohl waved his finger at Maxwell and started shouting at him.

Maxwell then turned and flung himself at Kohl, knocking him to the floor. The crowd gathered around and the Celtic bench emptied. Order was restored quickly and Maxwell was allowed to continue playing. No technical foul was called.

Maxwell was a key figure in the Philadelphia series as he guarded Julius Erving. He also played a key role in Boston's 98-95 victory over Houston in the first game of the final series Tuesday at Boston Garden. The second game will be Thursday night in Boston (shown on tape by WDVM-TV-9 at 12:30 a.m. Friday).

Maxwell went scoreless in the first half, but finished with 10 points, nine rebounds and five assists. The Celtics won the game because they were able to control the offensive boards and shut down Houston center Moses Malone. Malone made only four of 17 shots and scored 13 points. He had averaged 28.5 points in the previous 15 playoff games. Robert Reid picked up the scoring slack for the Rockets with 27 points.

The Celtics appeared to show the effects of their tough seven-game series with the 76ers as, at one point, they fell behind the Rockets, 22-8. They needed 18 points, 21 rebounds and nine assists from Larry Bird to help pull out the victory.

The Rockets, disappointed they lost a game they thought they should have won, said they aren't afraid of the Celtics or their tradition.

"All of their championship flags and retired jerseys hanging from the rafters is impressive," said guard Mike Dunleavy, "but they don't score any points for them."

"We know the Celtics and everyone else expects us to lose in four or five games and few people have much respect for us, but we belong here," said Houston's Calvin Murphy. "We'll have everyone's respect by the time this series is over."