The behaviour towards officers and match stewards from some fans at Monday’s cup tie derby between Preston North End and Blackpool was criticised as “disgraceful”.
Police said “a significant minority of determined people” from both sides were intent on causing trouble on the night and added that those identified would be tracked down and prosecuted.
The steward, wearing a hi-visibility jacket, was on the Deepdale pitch helping to clear Preston fans after their team’s late winner in the Capital One Cup game.
He was struck by a police horse as it cantered across the pitch, while another horse – also helping with crowd dispersal – seemed to clip him as he lay on the ground.
Two people were arrested for criminal damage to one of the supporters’ coaches outside the ground, with another four people held for minor offences.
Superintendent Richard Morgan said yesterday: “The behaviour of those involved in the disorder at last night’s game was completely unacceptable.
“There will be a thorough investigation over the coming days and weeks and I want to be very clear that those involved in the disorder can expect a visit from the police and to be prosecuted.”
Match commander Chief Inspector Nick Emmett said: “The behaviour of those involved in the disorder and the behaviour of some people towards officers and stewards was absolutely disgraceful.”
The Football Association said it is investigating the matter and will liaise with both clubs and the police.
Blackpool manager Paul Ince labelled the scenes at the match – which was broadcast live on Sky Sports – as an “absolute joke”.
“I understand that fans get excited... but who knows what can happen?” he said.
“We’re not listening. Has someone got to be stabbed before we listen?”
Club officials at Preston condemned the pitch incursion as “totally unacceptable” but said rival fans were not in contact with each other at any time during the incident.