NBA Commissioner David Stern said Thursday that the proposed blockbuster deal that would have the Boston Celtics sending the rights to Coach Doc Rivers plus forward Kevin Garnett to the Clippers, for center DeAndre Jordan and two first-round draft picks, is prohibited by the collective-bargaining agreement.

Stern said on an ESPN radio show that the league's collective-bargaining agreement doesn't allow a team to trade players "involving coaches' contracts."

"The only consideration that can be done here in player transactions are other players, draft picks and a very limited amount of cash," Stern said. "But coaches' contracts don't qualify as extra consideration or acceptable consideration in player transactions."

Stern said the Clippers and Celtics have had this "confirmed to them" over the last few days while they tried to broker the deal.

The Clippers contend these are separate transactions, but the league sees the proposal as a package deal involving Rivers and Garnett for a player and draft picks.

"What the rules won't allow … it can't be gotten around by breaking it up into two separate transactions," Stern said on the radio show.

As of late Thursday, the Clippers were willing to continue negotiating with the Celtics for Rivers even if L.A. can't get Garnett, said NBA executives who were not authorized to speak publicly on the matter.

The executives said the Clippers might now offer Boston just a second-round pick for the rights to Rivers, instead of a first-round pick.

Even if the Clippers and Celtics tried to break the trade into separate transactions — a deal for Rivers, and a second deal later involving Garnett — the NBA would frown upon that because there is an apparent linkage between them. "They are chasing the tooth fairy," an NBA official said.