The person spoke to The Associated Press on condition of anonymity on Friday because the ruling has not been made public.
Manziel said he was reacting to taunting by the Redskins during Monday night's nationally televised game. The action didn't help his chances to win Cleveland's starting job, which went to veteran Brian Hoyer. Manziel says he has to be "smarter" on the field.
Browns coach Mike Pettine was "extremely disappointed" by Manziel's conduct and said the 21-year-old's on-field behavior factored into the team's decision in naming a starter.