A parliamentary inquiry has found 'multiple failings' with the way Avon and Somerset Police handled the Kill the Bill protests in Bristol in March.
MPs and peers found officers had breached fundamental rights at the protest and failed to distinguish between those protesting peacefully and those acting violently.
The inquiry found police used 'excessive force' against peaceful protesters.
The force says it has investigated complaints around excessive force and they were not upheld, adding it "utterly rejects" the report’s suggestion that this use of force 'may amount to criminal offences'.
The all parliamentary group has also proposed amendments to the Police, Crime, Sentencing and Courts Bill, which is due to be debated on Monday, as a result of the findings.
Inquiry chairman, the Labour MP Geraint Davies, said the right to peaceful protest 'must be supported, not suppressed by the law'.
"The police must not become the enforcement agency of the state against those who choose to publicly and collectively call for change - political, economic, social or environmental.
"Parliament must protect our freedoms and reject attempts to increase police power and restrict our right to peaceful protest. The police should help to facilitate the expression of peaceful protest and not drive opposition underground."
The Kill the Bill protest in Bristol started peacefully but hours later turned violent as rioters clashed with police officers. Around 500 people marched on Bridewell Police Station with some setting fire to police vehicles and attacking the building.
The report found Avon and Somerset Police wrongly applied lockdown laws and their failure to give transparency and clarity about how they would enforce the regulations in respect of peaceful protest also breached fundamental rights.
The findings found the force 'failed to understand their legal duties in respect of protest' and 'failed to conduct a proper assessment of the proportionality of their actions'.
It said Avon and Somerset Police used 'excessive force' against peaceful protesters.
The report did acknowledge police were put in difficult situations due to the ambiguity of coronavirus rules.
Scrapping new proposed powers to limit the right to peaceful demonstrations has been suggested as an amendment to the Bill, alongside a code for policing protests as a result of the report. It found the new proposed powers to be unnecessary.
In response to the report, Avon and Somerset Police said: "During the period the report covers, the law was not sufficiently clear as to whether peaceful protest was lawful under Covid-19 regulations and all forces were interpreting them as best as they were able to.
"Complaints around disproportionate or excessive force relating to the use of shield strikes have been fully investigated by our Professional Standards Department (PSD) and the complaints have not been upheld and we utterly reject the report’s suggestion that this use of force 'may amount to criminal offences'."
They added: "We remain in the middle of one of the largest investigations ever carried out by Avon and Somerset Police, after police vehicles were damaged and set alight, officers were assaulted and our neighbourhood police station was vandalised during a riot.
"So far we’ve made 69 arrests with 21 people charged, of which 18 have been charged with riot. Three people have already admitted a charge of riot and await sentencing."