Alex Ferguson escaped with a warning over comments he made about a referee ahead of a crucial Premier League match, but could risk a touchline ban if he repeats the infraction.
Ferguson spoke positively about Howard Webb ahead of United's 2-1 win over Chelsea on May 8 but an FA regulatory commission says he was still guilty of improper conduct.
The FA prohibits managers from discussing officials ahead of matches. The FA says the "minor breach" was the first time the rule had been tested since it was introduced for the 2009-10 season. It added that "it should be taken as a warning to all managers in the future that any such breach, even positive comments, are likely to result in a charge."