Referee Mike Dean was left with a bleeding wound during Sunday's fiery Cardiff City vs Swansea City derby, and one man has been arrested in connection with the incident, according to Sky TV on Monday.
Chief Superintendent Josh Jones said officers will be "studying CCTV to identify further individuals who were involved in the throwing of missiles onto the pitch".
"The post-match investigation will aim to trace and arrest those individuals who became involved in incidents of disorder outside Ninian Park," he said.
The referee required medical treatment after he was struck in the 42nd minute of the 2-2 Championship draw.
Cardiff manager Dave Jones said the incident had overshadowed and soured a fantastic advert for Welsh football, saying that "it's sad because everyone will be talking about the man who threw the coin rather than a game which had everything - excitement, controversy and a last minute penalty."