Avon and Somerset Police will launch an investigation after Saturday's Championship game between Bristol City and Swansea was marred by clashes between rival supporters.
The force released a statement saying they will be investigating "attempts at co-ordinated disorder and incidents of criminal damage before, during and after the match".
Chief Superintendent Paul Mogg said: "It is very disappointing that a large group of Swansea fans seem to have arrived in Bristol with the intention of drinking to excess and seeking confrontation.
"There was disorder within the ground, with objects thrown by each group of supporters.
"There was further disorder after the match in Ashton Park and officers were deployed with dogs and horses to separate the two groups of fans.
"We've also had reports of damage at two pubs. These and any other offences which are disclosed will be thoroughly investigated."
Bristol City have launched a formal investigation into the clashes which occurred inside the stadium.
The club say two stewards and a police officer were treated for minor injuries and that a number of arrests were made.
Ashton Gate Stadium managing director Mark Kelly said: "Ashton Gate has a very strong record of match day safety and I can assure our fans that any home or away supporters that caused this unpleasant experience will be banned.
"The incident in its entirety was captured on CCTV and a formal investigation in conjunction with the Avon and Somerset Police match commander and our head of safety is under way.
"I would like to take this opportunity to recognise our safety team and stewards for taking control very quickly and dealing with this situation."