Robinson has not played in the Knicks' last 12 games. A two-time winner of the All-Star slam dunk contest, he has played in only 12 games this season and is averaging 11 points.
Agent Aaron Goodwin recently told reporters he'd asked the Knicks to move Robinson to another team. Robinson was fined for statements detrimental to the NBA.
"Players are not permitted to make trade requests publicly and are responsible for public statements relating to them made by their representatives," NBA spokesman Tim Frank said.
Goodwin said the benching was personal, not basketball related. A day after Goodwin's comments on Dec. 19, Knicks president Donnie Walsh said he would probably begin talks with the agent about a trade.
Goodwin didn't immediately respond to telephone and e-mail messages from The Associated Press seeking comment.
Robinson averaged a career-high 17.2 points last season as the Knicks' sixth man. He was a restricted free agent in the offseason and re-signed with a one-year contract.