He also caught Onuoha with a stray arm during the game, and then squared up to the player in the aftermath
But Ibrahimovic was only yellow carded and he apparently went into the opposition locker room to issue an apology.
"He came in to apologise after the game, because from 60 minutes in, he's saying he's going to do me, he's going to hurt me for that game," Onuoha said after the match to reporters.
"This is a guy who is the face of MLS, as he calls himself, and he plays that way on the field.
"If someone comes in and says that to me, I'm not going to accept his apology. It's unacceptable."