The European champions revealed they were fined 110,000 euros by UEFA for coming out for the second half of the game against Porto two minutes late and for the lighting of 10 flares by fans in the Stade Louis II.
Rosell was quoted as telling Onda Cero Catalunya: "We will comply with the law, but I think that one sanction is unjust and the other excessive.
"Regarding the matter of coming out after half-time , it's excessive because in a changing room many things happen during these minutes, players are going to the bathroom at the last minute...It's the law but I think it's excessive.
"But the sanction for the flares is worse because it's unfair. Barcelona cannot be responsible who brings flares into this stadium because Barcelona don't control who enters and who doesn't enter that ground. And what if they weren't Barca fans who had the flares?"
Rosell was also asked about the punishments handed down this week by the Spanish football federation to Real Madrid coach Jose Mourinho and Barca assistant coach Tito Vilanova for their roles in the mass brawl that marred the end of the Spanish Supercopa second leg in August.
Mourinho was handed a two-match ban after appearing to jab a finger in the eye of Vilanova, who was given a one-match ban by the RFEF for subsequently striking the Portuguese on the side of the head.
Both men were also fined 600 euros while the bans will be served only in future Supercopa matches.
Preferring not to get involved in the debate over those sanctions, Rosell said: "We have spoken with the sporting section and we've decided to continue doing our jobs and forget about everything else.
"All areas of the club are in agreement and we think that's what is best for Barcelona. Things are not always black and white. At this time, we're going to focus on ourselves, do our jobs as well as possible and forget all the other things."