The families had been protesting since 2012 against alleged atrocities by upper caste Jats in their village.
Late on Sunday night, several families from Haryana's Hisar, protesting at Jantar Mantar in the centre of Delhi for nearly three years, were allegedly driven out by the police who used batons.
Volunteers of former Aam Aadmi Party leader Yogendra Yadav's "Swaraj Abhiyaan" party, who were passing by, allegedly tried to step in and were also beaten.
The families had been protesting since 2012 against alleged atrocities by upper caste Jats in their village.
They allege that only when they announced that they were converted to Islam, did the authorities react.
Protesters and witnesses say at around midnight on Sunday, Delhi policemen tried to remove them by hitting them with canes.
"15-20 policemen attacked us at night, some were in civilian uniform. They hit me so hard my face is still numb. Police asked us to leave the protest site saying we have no permission. But we have nowhere to go...we have been evicted from our own village," said Jagdish, who says he has converted.
"We were lying down peacefully and have been protesting here at jantar mantar since 2012, no one bothered then, its only now that we have accepted Islam that the authorities have woken up to us. We had nowhere to go so we have embraced Islam," said another protester, claiming that over 100 dalits from his village converted on Friday.
The police action allegedly left about a dozen protesters injured; some of them suffered head wounds.
Volunteers of Yogendra Yadav's new 'Swaraj Abhiyaan' group preparing for a farmer rally saw the commotion and stopped to intervene. "I saw the police beating some protesters..I asked them why they were doing so? I intervened and they hit me on my head, they injured my finger too," said Manish, Swaraj Abhiyaan volunteer.
Yogendra Yadav said, "This is an astonishing case of brutality and illegality by Delhi police they attacked six of our volunteers. Because they happened to stand next to a place where the police were doing some kind of operation...they hit both our volunteers and the other protestors."