Two officers were injured as they broke up an "incredibly selfish" party, involving about 200 people, in one of London's most expensive neighbourhoods.
Officers investigated an address on Beauchamp Place, Kensington, at about 03.30 GMT on 17 January, following reports of a mass gathering.
Attendees became hostile and pushed through to avoid being fined, injuring two officers, police said.
No arrests were made.
The owner has previously been issued with a £1,000 fine, police said.
Supt Michael Walsh said: "Attending or organising such parties during this critical period is an incredibly selfish decision to make.
"While the majority of breaches have been resolved without incident, it deeply saddens me that some individuals have chosen to assault police who are simply doing their part in the collective battle against this deadly virus."
Police said the event was one of a string of late-night parties uncovered in Kensington over the last month.
On 20 December, police shut down an illegal gathering at a commercial property on Montpelier Street. The property has since been closed.
An owner of a venue on Harrow Road is facing a £10,000 fine after police found more than 30 socialising during a raid on 16 January.
On Thursday, police also broke up a wedding party in north London.
The Met Police originally claimed about 400 guests were at the gathering, but then on Friday said 150 people were present at the Yesodey Hatorah Senior Girls' School.