The Boston Celtics have had talks with point guard Rajon Rondo about a contract extension, president of basketball operations Danny Ainge said Thursday.

However, Ainge said the restrictive nature of the collective bargaining agreement makes it more likely that talks will escalate after this season,

"We did talk to Rondo about extending him," Ainge said during his weekly appearance on Boston sports radio 98.5 the SportsHub. "But that's all part of the negotiation that will happen again this summer and most likely the summer after.

"In the collective bargaining agreement, there are limits on what can and can't be done. Really, it's not that Rondo doesn't want to accept an extension, as much as it's just not financially smart for him to accept it right now. We didn't think he would (sign), but we did try."

Ainge said he did not want to discuss negotiation details through the media.

"I think that Rondo will demand quite a bit in the open market," Ainge said. "The competition for Rondo in free agency will be very high."

Next season will be Rondo's last from his five-year, $55 million extension that he signed in October of 2009.

Rondo returned last week from an almost one-year absence after tearing his ACL. He appeared in three games before sitting out Wednesday night's win in Washington as a precaution as he eases his way back and limits his minutes.

Rondo was also the topic of trade rumors less than a week ago.