Police arrest Barca fans following riots
Rioters overturning barricades, threw cans, bottles and stones at police, who responded with rubber bullets, television pictures from the centre of the city showed.
Radio station Cadena Ser reported that fans set rubbish containers alight and smashed windows, signs and traffic lights.
Police fired rubber bullets in an effort to disperse crowds in the city's main square and down its most famous thoroughfare, Las Ramblas, shortly after 2am local time, Cadena Ser said.
Ambulances took injured revellers away, a Reuters witness added.
Police estimated 100,000 fans gathered in the city's Catalonia Square to watch the match and celebrate the team's 2-0 victory over Manchester United in Rome, the third time the team has won Europe's top club competition.
Police were not reachable for comment.
Two weeks ago police arrested 45 people in the same area of Barcelona in violence following the team's victory in the King's Cup final against Bilbao.