The play happened under the Pelicans' basket in the third quarter after Cousins had secured a rebound. When Cousins raised his elbows near Westbrook's face, the Thunder guard dropped to the floor, holding his head. Westbrook remained sprawled on the floor for several seconds.
Replays showed Cousins slightly swung his elbow toward Westbrook, catching him on the back of his head near his neck without following through. Westbrook was OK and remained in the game.
Officials did not eject Cousins from the game until viewing replays on a TV at the scorers' table, after which they called a flagrant foul 2. Hard contact is not required for such a foul, only an act deemed reckless or dangerous.
"We didn't think it was that fair. He doesn't do anything intentional," Pelicans point guard Jrue Holiday said of Cousins. "We just wanted to win for him."
Cousins had 18 points, nine rebounds and four assists before his ejection with five minutes to play in the third. He ranks fifth in the NBA with 26.6 points per game and third with 12.9 rebounds per game.
New Orleans trailed 76-72 when Cousins was ejected but surged ahead soon after with an 11-3 run, during which Jameer Nelson, E'Twaun Moore and Darius Miller each hit 3s, with Nelson's banking in from near half court as the shot clock expired. Anthony Davis paced the Pelicans with 36 points and 15 rebounds.
Davis helped New Orleans end a two-game skid with his typical array of dunks, layups and clutch midrange shots. He also hit 18 of 22 free throws.
"It was tough losing [Cousins], being one of our star players, but anything is liable to happen in a game," Davis said. "So guys stepped up and were ready to play."
It was the second flagrant 2 of the NBA season but the second in two weeks.
On Nov. 5, Carmelo Anthony was given a flagrant 2 and ejected after contact with Portland's Jusuf Nurkic during a drive to the basket. Replays did not appear to show a convincing intent on the play by Anthony, who elevated into Nurkic and double-clutched, making contact to Nurkic's chin with his elbow.
Nurkic stayed down for a few moments while holding his face, which triggered the review.
The NBA later upheld the officials' call, saying Anthony's play "met the criteria of hard contact above the shoulders with high potential for injury" and was "dangerous and reckless in nature."
The Associated Press contributed to this report.