Barnsley have complained to the English Football League and Football Association following an alleged incident involving manager Daniel Stendel and Fleetwood boss Joey Barton.
The League One club said they are working with South Yorkshire Police and assisting with all enquiries.
Barton, 36, “physically assaulted” Stendel in the tunnel after Saturday’s loss at Oakwell, according to Barnsley player Cauley Woodrow on Twitter.
Woodrow later deleted the tweet.
On Monday, South Yorkshire Police said they were continuing to investigate reports of an assault at Barnsley Football Club.
“No arrests have been made at this time and enquiries remain ongoing,” a statement added.
Fleetwood said they had “been made aware of an alleged incident” and were “currently establishing the facts”.
BBC Radio Sheffield reported on Sunday that German Stendel, 45, was “OK” but “suffered facial injuries”.
Sky Sports News showed footage of Barton attempting to leave the ground after the match, but the car in which he was a passenger was stopped by police, before being allowed to proceed.
Barton later rejoined the rest of his team for the journey back to Lancashire.
The former England midfielder has a history of controversy, including a 77-day spell in prison for common assault and affray following an incident in Liverpool city centre in December 2007.
He took over at Fleetwood for his first managerial job last summer – one day after an 18-month FA ban for betting ended.