An early goal from John McGinn proved the winner on the night.
Arteta was left fuming late on and left the executive box before the final whistle in fury. The manager had been suspended for the game.
Arteta refused to explain what he meant by “clear and obvious".
But in a separate interview, on Havertz's disallowed goal, he said, “I prefer not to comment" and on the potential penalty, he added: “I think that one was even clearer."