A group of masked protesters became “aggressive” towards police at Canary Wharf shopping centre.
Police issued an order to “prevent people concealing their identity with masks” and made several arrests.
They said: “We have made three arrests for common assault, possession of drugs and assault on police/public order offences.
“One of our officers was punched in the face – luckily they have not suffered significant injury.”
The protesters have since dispersed, police said.
Video seen on social media showed young children among the protesters, with some of them wearing England flags.
Officers said: “We are aware there are young children in the protest area and while we deal with any criminality our officers are ensuring the safety of them is paramount.”
Police have also sent extra officers to deal with the demonstrations.
Follow our channel and never miss an update
Read more:
PM promises small boat migrants will be ‘detained and sent back’
Reform deputy leader disagrees with archbishop
Protesters from both sides of the divide over the UK’s immigration policies gathered outside the Britannia Hotel in Canary Wharf on Sunday afternoon.
Around a dozen anti-immigration protesters were faced down by about 100 counter-protesters holding banners saying “stand up to racism” and “stop the far right” on the other side of the road.
Demonstrators then left the hotel location – kept apart by police. It is thought that following this a group of protesters made their way into the shopping centre.
Sunday’s events in central London follow an incident in West Drayton on Saturday when a group of masked men were among those who attempted to enter a hotel housing asylum seekers.