The person spoke to The Associated Press on Thursday on condition of anonymity because the league hasn't announced the fine.
Newton shouted at and bumped referee Jerome Boger in the fourth quarter of Carolina's penalty-plagued 17-6 victory over the Oakland Raiders on Sunday.
Newton apologized after the game, saying "the words that I said during the game were very disrespectful and I apologized to (Boger) during the game, but I'm going public and apologizing again. It was something in the heat of the moment."
Boger said he didn't feel the bump was enough to warrant an ejection because it "wasn't of a malicious nature."