Trailing the play on a dunk by Sacramento's Ben McLemore, Terry put his hand out to slow down as he neared fans sitting along the baseline.
Andrew Rogers, Cousins' manager, slapped at Terry's arm. Terry stopped, turned around and started to step toward Rogers.
Officials reviewed video before ejecting Rogers from his seat.
"I don't know what happened. I didn't hear anything or see anything. That's all there is," said Terry, who clearly did not want to discuss the situation after the game.
Rockets interim coach J.B. Bickerstaff said the league has a responsibility to protect players.
"One of those guys put their hands on Jason Terry," Bickerstaff said. "If they don't want 'Jet' to react ... then you need to get those guys out of here. Just because players are on the court, it doesn't give the fans the right to say things and put their hands on them. ... They pay for their tickets but they can't put their hands on players when they step on the court."
Cousins also was reluctant to discuss the incident after the game.
"My biggest thing is, I didn't want the situation to escalate too far," he said, according to The Sacramento Bee.
"It just shows I've got some ride or dies," he added.
Terry finished with 14 points. Cousins had 26 points and 12 rebounds in the win. He also received a technical foul for a separate incident in the first quarter, one of three issued in the game.
Another fan, believed to be sitting with Rogers' group, was ejected later in the game.
The Associated Press contributed to this report.