UK police arrested nine people on Saturday following several incidents in and around three different protests held in central London, including a demonstration organised by far-right agitator Tommy Robinson.
London's Metropolitan Police said four people were arrested outside a pub in Westminster on suspicion of assaulting four officers.
"Fortunately none sustained serious injuries," the force said.
Earlier, officers arrested two men following an assault on a participant in an anti-fascism protest staged in opposition to Robinson's rally.
The pair were arrested on suspicion of assaulting the "Stand Up To Racism" protester in Victoria Embankment Gardens in the city centre.
Officers gave the victim first aid after he sustained a head injury in the incident, and he was taken to hospital to be checked, according to the Met, as the London force is known.
Meanwhile another man was arrested on suspicion of criminal damage and a racially aggravated public order offence after he allegedly snapped a Palestinian flag and made a racially abusive remark, police added.
Officers arrested another man on suspicion of assaulting an emergency worker and a racially aggravated public order offence after a police officer was kicked, the Met said.
The ninth arrest related to a suspected assault on a steward at a "Trans Pride" protest also held in the centre of the British capital Saturday.
The Met said around 1,000 officers were on duty as part of the "significant" policing operation to deal with the day's events.
Thousands gathered from late morning for the demonstration organised by Robinson, a far-right firebrand and founder of the now defunct Islamophobic English Defence League organisation.
The counter-protest staged by Stand Up To Racism and others also rallied nearby, with the Met imposing so-called conditions on the two marches "with the aim of preventing serious disruption".
They included requiring participants to stick to certain areas and streets and disperse by stipulated times.
In its latest update, the Met said videos had been shared online during the day showing chanting by some attendees at the Robinson rally which was "racist and anti-Muslim".
"It isn't always possible for officers to intervene in the moment, particularly within large crowds," the force added.
"However, that doesn't stop investigations taking place after events have finished to identify suspects and any offences. These videos are being investigated."