The protesters were stopped at Parliament Street as they left Jantar Mantar.
The leaders of the Sikh protesters were detained at the Parliament Street Police Station. There's heavy police presence in the area.
Various Sikh outfits also held protests in many parts of Punjab today. Rail traffic was disrupted for several hours across the state as activists of various Sikh outfits squatted on tracks to protest Mr Kumar's acquittal. (Read)
Delhi has been witnessing largescale protests since Mr Kumar was acquitted by a special CBI court on May 1. Many Sikh protesters shouted slogans against Congress president Sonia Gandhi as they held protest outside her home on Thursday. She was away to Karnataka to campaign for the state elections.
The demonstrators are furious that Mr Kumar was acquitted of all charges in one of three 1984 anti-Sikh riots cases against him. He was accused of murder and of instigating a riotous mob that killed five Sikhs in Delhi's cantonment area on November 2, 1984.
While finding Mr Kumar not guilty, the judge convicted five others in the same case, sparking anger among Sikh families who asked why the same evidence was not sufficient to nail the politician, who was a Member of Parliament when the riots tore into Delhi.
The protesters say they will not stop their street protests till the Central Bureau of Investigation (CBI), which prosecuted the case, appeals against the verdict in a higher court. The CBI has not yet decided its course of action.
Mr Kumar, who was then the Congress MP from Outer Delhi, is also accused of instigating a mob during riots in the Sultanpuri area. Six people were killed in the violence there.
The Delhi High Court is hearing Mr Kumar's petition challenging a trial court order to frame charges against him in the Sultanpuri case. He is also facing trial in another case related to anti-Sikh riots in the Nangloi area of Delhi.
The 1984 anti-Sikh riots broke out after the assassination of then Prime Minister Indira Gandhi on October 31, 1984. 3000 Sikhs were killed in Delhi alone. In the 29 years since the riots, only 30 people have been convicted, none of them high-profile politicians, though several Congress leaders have been accused of inciting violence.