Police were called to a house in Golders Green on Wednesday evening after reports of a wedding taking place there.
Video footage circulating on social media purportedly shows a couple taking part in a ceremony beneath a chupah in the garden.
In one video clip, a rabbi can be seen participating in the ritual, while in another the couple enter a room inside to the sound of music ushered in by a man with a microphone, a photographer and videographer.
Photos shown to the JC reveal a long, decorated table with 20 places and a number of round tables with chairs.
One passer-by on social media reported seeing a build-up of cars and people dressed in their Shabbat clothes "going in through the back door".
The Metropolitan Police said when they went to the address in Bridge Lane, NW11,in the evening, they were told a family occasion was taking place and that "a very small number of people would be present".
But they returned at 9pm following "reports of a large group of people gathered at the address".
Police said no arrests were made but one fixed penatly notice was issued.
They said they encouraged compliance with social distancing guidelines and by 11pm, the event had closed.
In another video clip, which appears to have taken during the first police visit, an officer inside the house remarks there were "loads of tables and chairs and not enough people."
When someone replies that people are social distancing, the officer retorts, "That's not the social distancing I understand."
The JC understands that another wedding celebration due to have taken place in Golders Green on Thursday night has now been called off.
A police liaison representative for the Jewish community said such events at the current time were "not acceptable".