The protest took place Friday near Rome's Colosseum, the Italian news agency ANSA reported.
Merchants and residents say Mayor Ignazio Marino's plan to close down part of the Via dei Fori Imperiali hurts their businesses, and residents say the plan will seriously affect their driving patterns.
Marino says closing the roadway to private vehicles will protect the Colosseum from pollution and make the area more pedestrian friendly.
Man spent 15 hours in jail for plugging electric car into an outlet at a school
Florida bear attack: Black bear mauls woman's face