Eight police officers have been injured as anti-lockdown protests in central London turned violent.
Demonstrators hurled bottles as officers attempted to disperse the crowds in Hyde Park on Saturday evening, the Metropolitan Police said.
Photographs posted on social media show a female police officer bleeding from a cut to her head, while another suffered a similar wound on his forehead.
The protests, which also took place on Oxford Street, come almost two weeks after Covid-19 lockdown restrictions were eased.
Five people were arrested for offences including assault on police and remain in custody, the Met said.
John Apter, national chairman of the Police Federation of England and Wales, tweeted: “These officers are just doing a job, they’re somebody’s son, daughter they’re mums and dads.
“To be targeted in the way they are says a lot about the society we’ve become.
“I will continue to do my best to support them but I need Government to do more, much more.”
Demonstrators held banners with messages such as: “Covid-19 Vaccine Holocaust”, and: “No To Vaccine Passports.”
Another banner read: “You don’t need proof to know truth.”
The force said both men had been taken into custody as inquiries continue.
Shoppers flocked to high streets and drinkers downed pints as coronavirus restrictions were lifted in England on April 12.
Prime Minister Boris Johnson urged the nation to “behave responsibly” as indoor gyms, swimming pools, nail salons and zoos welcomed customers back.
The documents would record – either on an NHS app or a paper certificate – whether someone has had a vaccine, a recent negative coronavirus test or natural immunity, having recovered from Covid-19.