Officers used defence spray to disperse a mob of some 30 people involved in a fight at the Quai Vernex and Jean Villard-Gilles on Saturday night at around 11pm, Vaud police said in a statement.
Two hours later, another riot broke out at the same place involving around 50 people, who threw glass bottles and other projectiles at police.
During this second event four police officers were injured and several cars parked in the area – including one police car – were damaged, as was a bus.
Fifteen people were arrested – 11 adults and four minors – for damage to property.
A total of 94 police officers and security staff attended the incident.
Videos taken by passers-by show police carrying riot shields walking down the street as objects are thrown at them, scenes more reminiscent of a violent demonstration than a music festival.
Yet nearby, people attending a silent disco as part of the festival were unaware of what was happening, according to paper 20 Minutes.
“At the silent disco I could not imagine what was happening just down the road,” one festivalgoer told the paper. “It was a great party, and yet 20 metres from there, it was hell. It’s only when I left the party that I realized.”
The silent disco was extended for an extra hour, until 4am, when shuttle buses that had been suspended due to the riots resumed.
Speaking to the paper Montreux mayor Laurent Wehrli condemned the violence and said he didn’t have the words to describe the “stupidity” of the behaviour.
But he stressed that the violence involved a “tiny minority” of those present. “We mustn’t think that all young people are like that,” he said.
The 51st Montreux Jazz Festival ended in the early hours of Sunday after two weeks of music events attended by some 230,000 people.
Chilly Gonzales, the Pet Shop Boys, Herbie Hancock, Beth Ditto, Sam Smith, Lauryn Hill and Tom Jones were among the big names that performed this year.