Six fans were stabbed and two were hit by bottles in violence ahead of Monday's Rome derby, according to La Gazzetta dello Sport.
The trouble began at the Milvian Bridge prior to Roma's 1-1 draw with Lazio at the Stadio Olimpico. Bottles and rocks were thrown while police used tear gas in a bid to quell the trouble.
"We are very concerned," Rome mayor Gianni Alemanno said after learning of the trouble on Monday evening. "I once again extend an appeal for calm: let's have a peaceful derby."
The ANSA news agency had reported that an ambulance had been abandoned after being attacked by fireworks, rocks and sticks, but Ares 118, which provides emergency services in Rome, later insisted that the vehicle had not been attacked.
Several people have been detained by police, while video footage is being assessed to identify others responsible for the trouble.
The Rome derby has a long history of problems, and in 1979 was responsible for the first violence-related death in Italian football as an 18-year-old Roma supporter fired a flare across the pitch and killed Lazio fan Vincenzo Paparelli. Derby matches in 2004 and 2009 were respectively abandoned and suspended due to problems involving the fans.