Initially a peaceful demonstration, the protest turned violent forcing police to cordon off the area around the Indian mission in central London.
The London police have apologised for their treatment of Sikh protesters during a demonstration outside the Indian embassy in the British capital last month
, a media report said on Sunday.
Mak Chishty, Metropolitan Police's chief of community engagement, said concerns had been raised by Sikh representatives about the actions of some officers at the October 22 protest, the Evening Standard reported.
The Sikhs were protesting over the recent deaths in Punjab and related incidents.
"An incident occurred where a Met Police officer is seen to take a flag sporting a religious symbol from a protester, snap the stick and throw it to the floor. This is deeply disrespectful to the Sikh community and is not acceptable.
"I understand the distress and hurt that has been caused and I sincerely apologise to our Sikh community for this," Chishty was quoted as saying.
A total of 20 people were arrested when the peaceful demonstration of a "small group of protesters turned violent towards police".
"I am also aware that 'kirpans' were removed from two people once they had been arrested. This was against the direction of the senior officer present who immediately apologised during the protest," the officer said.
He added that officers deployed during future protests involving Sikhs would be briefed on the significance of the religious symbol and 'kirpans'.
"I would like to reassure the Sikh community that no disrespect or offence was intended and apologise for any distress, hurt or offence that has been caused," Chishty said.