Ron Dennis has rebuked Sebastian Vettel for "inappropriate" comments about the new-look F1 and its 1.6-litre V6 engines.
With Red Bull Racing struggling to get the most out of their Renault engines and Mercedes taking over as the number one team, Vettel recently slated the new engines.
The German, who won four titles on the trot with Red Bull Racing, was vocal in his criticism and described the power units as "s**t."
And Dennis says that is not the way for a World Champion to behave.
"Being a World Champion requires a dignified approach to everything. Putting aside the language for the moment, the sentiment is inappropriate," the McLaren chief told The Guardian.
"He should reflect he has had a period of dominance and just because it has been somewhat shaken by Mercedes Benz doesn't give him licence to be disrespectful of the obligations placed on him as World Champion."