South Yorkshire Police are investigating an incident in the tunnel after Barnsley's match against Fleetwood at Oakwell.
Barnsley striker Cauley Woodrow tweeted that Fleetwood manager Joey Barton confronted Barnsley manager Daniel Stendel following the game, which ended in a 4-2 victory for the home team.
The tweet has since been deleted.
A South Yorkshire Police spokesman said: "We are aware of something that has taken place in the tunnel after the game and we are investigating."
Neither club fulfilled their post-match media duties after the match, which saw Fleetwood have Harry Souttar sent off after 65 minutes with Barnsley leading 2-1.