Barcelona will make tickets for European games at the Camp Nou non-transferable after a reported 30,000 Eintracht Frankfurt fans flooded Camp Nou.
Fans entered the Europa League game venue despite away fans only being allocated 5,000 tickets.
President Joan Laporta said after Barca was knocked out of the competition on Thursday by the Germans in the quarter-finals after winger Filip Kostic scored twice in a 3-2 victory that saw Eintracht advance 4-3 on aggregate.
While Barca was expecting huge backing at the stadium, ESPN reported there were close to 30,000 Eintracht fans among the 79,468 crowd.
Of those who attended the game, the club said that 37,746 were season ticket holders, 5,000 tickets were in the away section, and 34,440 had bought tickets through other means. European soccer's governing body UEFA invited the remaining.
"We insist that the 34,440 tickets that went on sale were tickets restricted to sale outside Germany," the club said on Friday.
"The club did not sell tickets to German fans. Who bought those tickets, did so and passed them on to German fans, that is obvious."
Laporta said Barcelona "is not guilty" for events leading to the tickets ending up in the hands of German fans.
"However, we do assume the responsibility that falls to us," Laporta said.
"We do not want this to happen again at Barca, and we will take action: The measures that I can announce and that we have adopted are that for international competition, tickets will be non-transferable.
"The club is not to blame for people breaking the rules, we applied all the measures we could to avoid it," he added.
"But there are people who consider that they have to do it despite the damage to the club and the fans and members who came to support the team at Camp Nou."


Iran women soccer players thank Australian government for protection
Villa's Watkins looking to make late push for England World Cup squad
Former Arsenal, Juventus goalkeeper Manninger dies in road accident
French Open prize money increases, retiring players to be honoured
David Beckham: Inter Miami not rushing to replace head coach
