The Congressmen held the demonstration at Kasturchand Park Ground square, close to the venue where Modi was laying foundation stone for Nagpur Metro Rail project.
At the event, Vidarbha statehood supporters raised black flags.
According to Congress workers, they were protesting against the booing of their leader and Maharashtra Chief Minister Prithviraj Chavan at a public function in Solapur last week, where Modi was also present.
The protest was led by Congress' Nagpur unit President and former Mayor Vilas Thakre, former Minister Anees Ahmad and Corporator Prashant Dhawad, among others. The party workers also raised anti-Modi slogans.
Policemen moved in and dispersed the protesters, who were also detained, police sources and eyewitnesses said.
Thakre, when contacted, told PTI that police used force to disperse them.
During Modi's speech at today's event, some women, all supporters of separate Vidarbha, raised black flags, demanding statehood for the region. They were taken into custody by the police.
At the Solapur event related to a highway project on Saturday, Chavan's speech was disrupted mid-way due to chants of "Modi! Modi" by a section of the crowd.