The midfielder is still fuming after a vital Lionel Messi goal was incorrectly ruled out by referee Antonio Mateu Lahoz for offside.
Messi was judged to be offside as the ball came to him with officials thinking that Fabregas was the last one to touch the ball.
But replays showed that Atletico Madrid defender Juanfran touched the ball last.
If the goal was allowed to stand then Barcelona would have beaten Atletico on the final day of the 2013/14 season and sealed the league title.
However, the game finished 1-1, handing the trophy to Atletico.
And Fabregas – who was hoping to pick up his second Spanish LaLiga title – is still annoyed about the mistake.
He said: “They took away a league against Atlético de Madrid from me.
“I was in the game and they annulled a goal that was legal, because I didn’t touch the ball, Juanfran touched it.”
Former Barcelona assistant manager Elvio Paolorosso even revealed that Lahoz admitted his mistake and apologised to the team after the game.
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He said: “Messi scored a goal that would have given us the title and the referee ruled it out.
“We were crying in the dressing room and the referee came to apologise.”
The midfielder left Barcelona following the end of the season and returned to the Premier League by joining Chelsea.
He is now playing for Serie B side Como after a three-year stint with AS Monaco.