Officers yesterday released CCTV footage of a number of men they believed were involved in disorder.
Graff diamond heist: two remanded in custody over Britains biggest jewel robberyFour arrests were made yesterday in Manchester and a further three were made today - two in Oldham and one in Preston. They were arrested on suspicion of conspiracy to commit violent disorder.
Further arrests are expected throughout the day.
Detective Chief Inspector Mark Roters said: "Many families, including women and young children, attend football matches so it is totally incomprehensible that a small number of mindless thugs would incite violence when they are surrounded by people clearly terrified by their actions.
"Football-related disorder is a stain on the game and we have been working hard with both clubs and members of the public to identify those involved.
"These arrests also act as a strong warning ahead of the reverse leg this evening to anyone prepared to get involved in this type of behaviour that we will come after you.
"I would also like to thank the public for their great response to the appeal."
Eighteen arrests were made last week after the match and appeals have been made by the police and the Football Association for calm ahead of tonight's game.