"What happened some weeks ago in Washington DC and what happened yesterday (Saturday) in Marseille follow a comparable logic," McCourt wrote in a statement on the club's website on Sunday.
"A few sources feed an inferno of opinions, invectives, and threats that are amplified by social media creating the conditions that lead to violence and chaos," he stated.
French prosecutors said 18 people remained in custodyfollowing the attack by several hundred disillusioned supporters that caused widespread damage.
The hardcore Ultras, who were demonstrating against the club leadership and the team's poor recent run of results, assembled in front of Marseille's La Commanderie training ground on Saturday afternoon, throwing smoke bombs and firecrackers.
"A frenzy of unjustifiable violence put the lives of those present in danger," a club statement read.
"Theft was committed and vehicles damaged. Five trees were burnt down...several hundred thousand euros worth of damage was caused."
The Mediterranean city's public prosecutor Dominique Laurens said investigations were "continuing throughout today (Sunday)" into the violence which led to the postponement of the club's Saturday evening Ligue 1 fixture against Rennes at their Velodrome stadium.