A video which appeared to show a woman being arrested for breaching lockdown rules by sitting on a bench was "staged-managed", say police.
The footage was widely-shared online as example of over-zealous officers cracking down on people suspected of flouting coronavirus regulations.
It featured a woman being handcuffed and led away in Bournemouth on Saturday as she repeatedly tells police: "I was sitting on a bench".
Dorset Police said that officers were left with no choice after a group of anti-lockdown protesters refused to provide their details when asked.
Two of them were released after providing the information and issued with fines, while the third was fined after their details were verified in custody.
"We believe this video was planned, stage-managed and recorded by members of the protest group who turned up in multiple areas, several of whom refused to engage and provide their details," said assistant chief constable Mark Callaghan.
"If people refuse to give their details in such circumstances then it leaves officers with little option but to arrest until the details are established.
"Our officers would only arrest as a last resort."
A total of seven fixed penalty notices were issued to those who breached lockdown rules on the day, the force added.
Mr Callaghan said officers were "astonished" that some of the group had travelled from outside Dorset despite current lockdown guidance to stay at home.
He added: "It was clear that the group were deliberately organising their activities, walking around in twos and then trying to come together in a 'flash mob' style approach, as they have done previously," he said in a statement.
"This activity went on for a couple of hours."
He said officers had acted "with professionalism, integrity and restraint in difficult circumstances" and that the arrests were "proportionate, justified and correct".
Questions were raised over how the police were enforcing the rules after Derbyshire Police fined two women £200 each over the weekend for driving to a beauty spot five miles from their homes for a walk - with one saying she had been informed by officers that in bringing a hot drink the meet up was “classed as a picnic”.