Lincoln boss Danny Cowley has accused Forest Green goalkeeper Bradley Collins of spitting at defender Sean Raggett.
Chelsea loanee Collins, 20, was at the centre of an ugly confrontation late on in Tuesday's League Two match, which the Imps won 1-0.
"Their goalkeeper spat at Sean Raggett, so that's what is all started from. We are categorical on that," Cowley told BBC Radio Lincolnshire.
The Football Association have told BBC Sport they are aware of the allegation.
BBC Sport also contacted Forest Green but they are yet to comment.
"I am not hiding from it. That's what he did and our players reacted as a consequence of that," Cowley added.
"We always want them to keep their discipline but sometimes when you are provoked like that, then naturally you can lose your cool.
"I think Sean lost his cool and a few of ours that saw it did as well and that created what it created, but it was instigated from their goalkeeper who spat at Sean Raggett."