It comes amid reports six Liverpool fans have been arrested in Catalonia.
Two workers at the Placa Reial hotel were allegedly assaulted and required medical attention, while two others suffered bruises, including a broken nose, according to reports in Mundo Deportivo.
Spanish newspaper Sport reports that fans threw objects at police and that nearly 3,000 cans of beers, to be sold around the busy square, have been confiscated.
But Liverpool fans have taken to social media to accuse the Spanish police of 'hugely over-reacting'.
6명이서 직원 2명 코 박살내는 등해서 체포당함
광장에서 경찰에게 여러 물건들을 던져서 팔릴 3000여캔 맥주 몰수
리버풀팬들은 오히려 소셜미디어에서 스페인 경찰이 오버액션한다고 비난