Ryan Roberts, 25, told one officer driving a van that he was going to "go bang" while he played a "leading role" during the protests in Bristol on March 21 this year.
Video footage showed Roberts holding a piece of burning cardboard under a police van, which had seven officers inside, as it was reversing away from rioters.
He was also seen attempting to start a fire under the wheel arch of a police van with an officer inside.
On October 29, Roberts was found guilty of five offences in relation to the 'Kill the Bill' riots in March. He will be sentenced at a later date.
Jurors were shown a 34-minute video compilation of his offending, which included CCTV, mobile phone footage and officers' body-worn cameras.
Wearing a dark hoodie, Roberts was seen on the roof of the Bridewell Police Station leading offensive chants about police to a jeering crowd.
He was then captured throwing missiles at police officers, kicking their shields and striking one with his hand before attacking the Bridewell.
Roberts was later filmed trying to start a fire under the wheel arch of a police van with an officer inside. At one point he is heard threatening the officer, suggesting his van is going to explode.
He was then filmed repeatedly hitting an officer with a police baton before damaging three police vehicles, one of which he tries to roll over with others before starting a fire inside.
Other video clips showing Roberts moving a bin alongside a police car before setting it alight and throwing items, including large metal fences, at police lines were played to jurors.
Roberts, of no fixed address, was found guilty of riot, attempted arson with intent to endanger life and attempted arson being reckless as to whether life is endangered.
He was also found guilty of two counts of arson being reckless as to whether life is endangered.
Detective Superintendent James Riccio, the senior investigating officer, said: “Ryan Roberts played a leading role in one of the most shameful nights in Bristol’s recent history.
“He denied all the offences and blamed police for his actions but the footage we found of his involvement in the riot spoke for itself.
“Not only did he repeatedly target officers physically, hitting and kicking them and throwing large objects at them, but he attempted to set fire to vehicles with officers inside.
“The most horrifying aspect of this offending is that he wasn’t simply trying to burn the vehicles, he was knowingly endangering officers’ lives and the lives of others in the area.
“These are officers who come to work every day to protect the public, they should never be assaulted and should never have to face threats or attempts on their lives.”
James Le Grys, crown advocate for CPS said: “Six months on, this incident remains shocking due to the levels of violence used by those who hijacked an otherwise peaceful protest.
“Ryan Roberts was one of the main offenders and the violence he used extended to attempting to set light to an occupied police vehicle.
"Today he’s been convicted for his part in the dreadful scenes caught on video.
"We’ve worked closely with the Police to deliver a coordinated response and support what has been a complex investigation.
“We respect the right to legal protest but when people resort to violence and destruction we will charge offences that reflect the gravity of the criminality.”
Criminal proceedings relating to the disruption on March 21 are ongoing against other defendants.