A police officer was injured while attempting to break up a street party of around 200 people in east London celebrating Eid, it was reported on Saturday.
Officers were called shortly before midnight on Thursday to Ilford in east London, the Metro newspaper reported.
The Metropolitan Police received calls from the public who had spotted a large group of people gathered on the street ahead of Eid.
Officers approached the crowd and asked them to go home, but as some people dispersed a fight broke out.
Police rushed to break up the fight between the two groups and one officer suffered a head injury in the commotion.
One man was arrested on suspicion of a public order offence and assaulting an emergency worker.
Chief Superintendent Stephen Clayman, of the Met's east area command, said on Friday night that he was "concerned" about the size of the gathering during the coronavirus crisis.
"While we accept that celebrations take place, and we have no desire to spoil them for the community, if they descend into violence we absolutely will step in," he was quoted as saying by the Metro newspaper.