Four men have been arrested during a series of raids following violence in Nottingham before and after Forest's FA Cup tie with Leicester City.
The disorder on 6 February saw groups, who were heard singing Leicester City chants, throwing chairs and tables.
Police said warrants were executed at five Leicestershire homes on Friday to arrest suspects thought to be involved in violence outside the Fat Cat bar.
Four suspects are being held on suspicion of violent disorder.
Meanwhile, during the game - which Nottingham Forest won 4-1 - Leicester City fan Cameron Toner ran on to the pitch and attacked Forest players as they celebrated the third goal.