Emergency services were deployed to Bonn's central station on Saturday night after clashes between "left-wing and right-wing groups," police told German news agency dpa.
The western German city's station was temporarily closed, with roads blocked and rail traffic suspended in both directions.
Police said some people fell down onto the train tracks during the scuffles, but that no one had been injured.
The violence followed an annual demonstration by neo-Nazi activists in Remagen, about 23 kilometers (14 miles) south of Bonn. Police said around 130 people had taken part in the afternoon event, while up to 900 others had joined a counterdemonstration.
The fighting broke out at around 6 p.m. local time (1700 UTC) when a train carrying a number of protesters pulled into Bonn.
Authorities said they had launched investigations into serious breaches of the peace, among other charges.