Bhim Army chief Chandra Shekhar Azad was taken into police custody from the gates of Jama Masjid in the early hours of Saturday.
He was inside the mosque after the protest against the Citizenship (Amendment) Act, which took place at Jama Masjid on Friday.
"We have to make sacrifice so that the legislation is taken back. We do not support violence. We were sitting inside the mosque since Friday morning and our people were not involved in violence," he said.
Azad had managed to escape from the police after being detained at Jama Masjid following the protests. After Friday prayers ended at the mosque, a massive protest started from the Jama Masjid in the old Delhi with Bhim Army chief Chandra Shekhar Azad leading the chants of "Jai Bhim" and holding placards with Babasaheb Ambedkar's posters.
They were denied permission for the protest march from Jama Masjid to Jantar Mantar earlier.
The protests were in continuation of those taking place across the nation against the just enacted Citizenship (Amendment) Act and the National Register of Citizens (NRC).
Demanding withdrawal of the CAA the protestors held up copies of the Constitution and pictures of Dr Bhimrao Ambedkar and Paramveer Chakra awardee Abdul Hameed. The crowd swelled despite a prohibitory order in place.
With the national flag held high, the protesters shouted slogans like "Hindustan Zindabad!"
Protests against CAA and NRC have been going on across the country in several states and cities despite section 144 being in place in parts of Delhi, Uttar Pradesh, and in Karnataka. It prohibits assembly of more than five people in a public place.
Thousands of people have been taking to the streets, and while the protests have largely been peaceful, there have been sporadic incidents of violence between police officials and protesters. In Mangaluru two people died after police fired on the protesters, and 11 others are injured.
With PTI and IANS inputs