The footballer received a £2,500 ($3,400) fine from a regulatory commission, having been charged with misconduct under Rule E1(b) in respect of 53 bets placed on football matches in November 2020.
None of the bets were placed on a match that involved the League One club, while one of the bets involved the FA Cup, a competition that the club participates in.
The commission has, however, come to the conclusion that, having recently arrived on loan from a club in Denmark, Nicolaisen was unaware of the different betting rules in place in English football.
“Portsmouth Football Club believes the player acted in good faith and this was a result of a misunderstanding over the different regulations in England and Denmark,” a statement from Portsmouth FC read. “Rasmus has been professional in all aspects since his arrival at Fratton Park last summer.”
The statement continued: “The club has made it clear to all players and staff members that they are prohibited from betting – either directly or indirectly – on any football match or competition that takes place anywhere in the world.”