World Rugby tweeted: "TMO can't be used to determine if a penalty should or shouldn't be given. Only for offences is build-up to a try, foul play or scoring of a try."
Foul play is anything a player does within the playing enclosure that is against the letter and spirit of the Laws of the Game. It includes obstruction, unfair play, repeated infringements, dangerous play and misconduct which is prejudicial to the Game.(WR definition)
Deliberate offisde is foul play.