It has been alleged that Mackie aimed a punch at Asaba in the tunnel as the players trapsed off following Reading's 2-0 defeat at home to Sheffield United.
It has also been reported that the incident continued when the players came back out onto the pitch to warm down, with the pair reportedly having to be separated by a stweard.
It is understood that match referee Mike Riley saw the incident and will include it in his report of the game that will be filed to the FA in the next few days.
The 26-year-old former Crawley Town player will then face an anxious wait before hearing if he will face disiplinary action over the alleged incident.
John Mackie, who started the season as club captain before falling out of favour at the club, is thought to have been upset about an alleged elbow in the face he received from Asaba in the dying minutes of the game.
Suspiciously, when asked to comment on John Mackie's performance in the post-match press conference boss Alan Pardew, who is often keen to talk players performances up, merely commented: "He did OK," possibly suggesting he was not happy with the centre-backs conduct.