The policy represents the N.B.A.’s first attempt to curtail flopping, after years of complaints by fans, coaches and players. Commissioner David Stern has long pushed for a crackdown, but he had to convince the owners first.

“We’re hopeful that it has an impact on behavior on the floor,” Jackson said in a telephone interview. He added, “It’s a big enough problem that we felt strongly it needs to be addressed.”

Many players agreed.

“It’s going to clean up the game a little bit,” Nicolas Batum of the Portland Trail Blazers told The Oregonian. “Everybody flops sometimes, and if this cleans up the game, that’s great.”

The Knicks’ Amar’e Stoudemire called the crackdown “a great thing,” adding, “It takes out some of the acting on the court.” His teammate Tyson Chandler said, “There are a lot of guys in the league that are in trouble.”

The league will define flopping as “any physical act that appears to have been intended to cause the referees to call a foul on another player.” Officials will make their judgment based on whether a player’s “physical reaction to contact” is “inconsistent with what would reasonably be expected, given the force or direction of the contact.”

However, the league clarified that “legitimate basketball plays,” such as “moving to a spot in order to draw an offensive foul,” as well as minor reactions to contact, will not be punished as flops.

Although the fines are not particularly onerous, the shame of being publicly labeled a flopper might be an effective deterrent. Flopping is generally viewed by players as a cheap trick — or, more bluntly, a “chump move,” as Kobe Bryant said in an interview with Los Angeles reporters.