The National Basketball Association, reacting to complaints by college coaches that it has been enticing nonseniors to leave school, approved a rule yesterday banning contact between NBA teams and undergraduates before the draft.

The rule is designed to prevent NBA teams from making specific offers to undergraduates before they decide whether to declare themselves eligible for the draft.

"Colleges claim our teams are tryng to entice players out," said Joe Axelson, the NBA's director of operations. "This is an indication of our sincerity that such a decision (whether to leave school) should be made by the players themselves. We don't want to appear to be the villains in this thing."

Exactly, said Maryland Coach Lefty Driesell, who criticized the NBA harshly after Buck Williams decided to pass up his last year at Maryland to turn pro in the fall.

"They're not doing this to help us, they're doing it to help themselves, make themselves look good for one thing," Driesell said. "They don't care about us. There are going to be three undergraduates (Williams, Isiah Thomas and Mark Aguirre) picked in the first five players this year. I'm not sure they would go so high or cost so much if they didn't have to guarantee them money to make them come out."

Driesell did concede that the new rule "could help a little but only if it keeps the agents from talking to the league about players."

Under the working of the new rule, any contact, direct or indirect (read agent), with a player will be illegal.

Axelson took a shot at the colleges in announcing the rule change. "It's also up to the NCAA," he said, "to clean its own house."

In the meantime, it seems possible that Maryland's Williams will be the first player selected in the draft next week. Isiah Thomas, the Indiana guard, has made it clear he does not want to play in Dallas and Maverick Coach Dick Motta, who has the first pick, visited Maryland recently to talk to Driesell and Williams and look at films of the player. The 6-foot-8 forward would fill a very definite Dallas need.

The NBA voted several rule changes yesterday, the most significant regarding bonus free throws. No longer will players shoot three to make two or two to make one after the fifth foul of a quarter and no longer will a back-court foul be a shooting foul unless a team is over the limit.

The league also adopted six changes involving zone defense, including a ban on double-teaming from the weak (nonball) side and a rule that prohibits a defensive player from being in the lane more than three seconds unless he is guarding a player in the lane or a player posted next to the lane. u

It was announced that Deputy Commissioner Simon Gourdine would resign when his contract expires in January 1982. Gourdine, the highest-ranking black executive in any major league, said he planned to pursue opportunities in legal, corporate or government areas.