Police were called to Cecilia Road, Lambeth on the evening of Wednesday, 24 June to multiple reports of a large unlicensed music event in the street.
Officers attended to encourage the crowd to leave the location but they did not engage with police.
The event continued and more officers attended the scene and the group became hostile towards officers.
A Dispersal Zone was authorised under S35 of the Anti-Social Behaviour Crime and Policing Act 2014 to encourage crowds to leave.
In total, 15 officers were injured, none seriously although two did require hospital treatment.
A small number of police vehicles were damaged.
Four arrested were made for assault and public order offences. They remain in police custody.
The event was cleared in the early hours of Thursday, 25 June.
A section 60 was later implemented in the vicinity of the event to prevent violence.
BCU Commander Colin Wingrove said: “Our role is to protect the public and ensure guidelines are adhered to in order to prevent the spread of Covid-19 protecting the NHS and save lives
“Our officers work incredibly hard to engage and explain the public health message and regulations to prevent such gatherings occurring.
“Last night we received numerous concerns from residents complaining about a large gathering, noise, anti-social behaviour and violence and officers responded to those concerns.
“These gatherings are unlawful, as well as posing a risk to public health and against coronavirus restrictions.
“The violence shown towards officers is totally unacceptable and we will not tolerate it in any form.
“An investigation into the incident is now taking place and those involved will be brought to justice.”