In a statement the Spanish champions said yesterday that they would do everything to overturn a punishment which they described as "totally unjust and...Opposed to the exercise of the freedom of expression."
Of the fine, 50,000 euros will be suspended if there is no repeat offence in the next two years.
The Catalan 'estelada' -- which differentiates from the red and yellow Catalan flag by the presence of a five-pointed star within a blue triangle -- has in recent years become a symbol of the independence movement within Catalonia.
The club was also fined 30,000 euros in July 2015 after it was flown during the Champions League final in Berlin the previous month, where Barca beat Juventus to lift the trophy.