A self-styled “yellow vest” protester has been fined for assaulting a journalist at a demonstration in Manchester.

James Goddard, 29, a pro-Brexit activist, grabbed a camera belonging to Joel Goodman, a news photographer, at a yellow vest event in Manchester city centre on 9 February.

At Manchester magistrates’ court on Tuesday he was found guilty of common assault and fined £300. He was also ordered to pay £500 in prosecution costs, £50 compensation to Goodman and a £30 victim impact surcharge.He was cleared of using threatening words or behaviour to cause his victim to fear immediate violence.

Goddard had denied the charges against him and represented himself in court. He was accompanied at the hearing by about a dozen supporters, three of whom were asked by the judge to leave.

The court heard that Goddard had nine previous convictions including theft from an employer and failing to surrender in April 2010, and a racially aggravated public order offence in February 2011.

The hearing was adjourned briefly after Goddard held up a piece of paper with the words “Pussy coward leftist soy boy”, unseen by the judge or court officials at the time. During the short break the piece of paper was seized by police officers, who were harangued by Goddard’s supporters calling them “bullies” and “jobsworths”.

When the hearing resumed, the district judge Mark Hadfield said there had potentially been an offence under the Contempt of Court Act but he had chosen not to pursue the matter.

Goodman told the court he was working a shift for the Manchester Evening News covering a protest and counter-protest at Piccadilly Gardens when Goddard approached him.

Goodman was wearing a bodycam, and the court was shown footage of Goddard appearing to lunge at him and twice trying to grab his camera. Goodman backed away shouting: “Don’t you dare touch my lens.”

Goodman told the court Goddard approached him again about 20 minutes later. Goddard was filmed telling Goodman: “When there’s no police around here I’m going to take your head off your shoulders. Next time you are in London, you are finished, all the football lads know you. Next time you are down, see what happens.”

Lynn Rogers, prosecuting, asked the witness: “How did you perceive those words?” Goodman replied: “Meaning to assault me in future. It scared me a bit.”

Using a megaphone and surrounded by yellow vest supporters, Goddard was then recorded referring to “Joel” and saying: “Your card is marked.”

A further 20 minutes later there was a third encounter where the two argued about freedom of speech and the right to protest, and the right of Goodman to take photos.

Goddard was arrested five days later at his home address in Timperley, Greater Manchester. He made no comment and later claimed self-defence.

On Tuesday he was given a two-year restraining order banning him from making any contact with Goodman.