Noah did not return to the game and left the United Center in a sling. Coach Fred Hoiberg called the injury a shoulder sprain.
"I just felt it pop out, and it went back in," Noah said. "We got the X-ray, and X-ray came out negative, so that's good news."
Noah said the injury was "pretty painful" and was scheduled to undergo an MRI on Tuesday.
The injury occurred when Noah became tangled up with Nets big man Andrea Bargnani. Noah immediately clutched his left shoulder as his arm hung near the ground.
Noah was escorted to the locker room by members of the Bulls training staff. He had four points, eight assists and eight rebounds in 15 minutes of play before his exit.
A ninth-year veteran, Noah is averaging career lows this season in points per game with 4.5 and field goal percentage at .404.
Bulls point guard Derrick Rose said it would be "devastating" if the Bulls lost Noah for an extended period.
Big man Pau Gasol agreed but said it could serve as "an opportunity for another guy to step up and show what you can do and compete and do what you can to help the team win."
"He's an important player," Gasol said. "Brings a lot of energy to what we do, which is one of the things we lack of a lot times. So if he has to miss games obviously it will be harder without him."