The two clubs and local authorities were unhappy that French Professional League (LFP) president Frederic Thiriez had waited until Sunday lunchtime to postpone that evening's match when 2,000 PSG supporters were already on the streets of Marseille.
Several PSG players had been diagnosed with H1N1 flu and the rest of the Ligue 1 team were quarantined.
"The decision to postpone the game was taken thoughtlessly and too late," Marseille chairman Jean-Claude Dassier said on the club's website. Coach Didier Deschamps added that the postponement of the game "was difficult to understand".
PSG chairman Robin Leproux criticised the LFP for having "hastily decided on Saturday that the game should be played".
Soon after the League decision was announced, Marseille and PSG fans clashed near the Vieux Port, in the historical centre, and the main railway station.
Police, who had been deployed in large numbers because the match between the arch rivals was regarded as a high-risk game, fired tear gas and baton charged, needing several hours to restore peace.
Police said 20 people - 10 supporters and as many policemen -- were slightly injured, and 18 were arrested, 15 in Marseille and three more at motorway services ransacked by PSG fans travelling back by bus.
"Among the people arrested, 14 will face trial immediately, the four others have been released," Marseille prosecutor Jacques Dallest told Reuters.
"FAIT ACCOMPLI"
Local police chief Philippe Klayman said he had been "presented with a fait accompli".
"The French League could have made the decision yesterday (Saturday) so that many PSG fans would have stayed home," he said.
Thiriez said the League had followed the recommendations of the national commission of medical experts.
"I took the right decision at the right time," he was quoted as saying by sports daily L'Equipe.
"We consulted the commission on Saturday and they said that two PSG players (Ludovic Giuly and Mamadou Sakho according to a PSG spokesman) had been diagnosed with H1N1 flu but the match could be played as scheduled.
"Another case (Jeremy Clement) was diagnosed late on Saturday and two more (player Loris Arnaud and coach Raphael Fevre) on Sunday morning. To suggest the clashes were linked to the postponement of the game is pure intellectual swindle."
Faced with another headache about the new date for the game, the League turned down Marseille's request to play on Wednesday, pointing out that all PSG players and staff had been quarantined for 72 hours.
"Unless we reverse the decision of the commission, it's unthinkable to put that team on a plane on Tuesday or on Wednesday morning. The replay date will be announced on Thursday," the League said in a statement.
Marseille have threatened to field their B team if the match was rescheduled for a later date because it could clash with the Champions League and the African
