The 54-year-old attacked the boys aged 14 and 15 at News and Food Express in Chalk Farm, north London, on 17 October.
District Judge John Zani, passing sentence at Westminster Magistrates’ Court, handed down a 10-week jail term suspended for two years and a £1,080 fine, and ordered that he must attend a rehabilitation programme which aims to reduce violent behaviour.
Joyce, the former MP for Falkirk, insisted at the trial earlier this month that he was performing a citizen’s arrest’ but the judge found him guilty of two counts of common assault.
Prosecutor Jonathan Swain told the court that it was an “unjustified and unprovoked assault on both boys”.
Joyce grabbed the 14-year-old and knocked him to the floor and continued to hold on to and wrestle the boy.
The second boy tried to help his friend but was elbowed by Joyce and winded.
Joyce was convicted in 2012 of four common assaults in a House of Commons bar – which led to his resignation from the Labour Party – and last year of breaching the peace at Edinburgh Airport after being “threatening and abusive”.
In passing sentence for Joyce’s latest attack, Judge Zani said: “In my view, the evidence against you was very overwhelming and the defence that you put forward was lacking in any credibility, particularly when one looks at the CCTV evidence.
“Your interpretation of what that demonstrated, I’m afraid, vastly differed from the way I saw the events portrayed.” He went on: “The events in October 2014 did you no credit. Your reaction to what you perceived was happening in the shop was entirely unacceptable.”
The judge told him that he must ensure he avoids violence in the future.
He said: “I consider that you have dealt with your alcohol problem and you need to focus on dealing with situations where there is a requirement for you not to resort to violence.”
Joyce stood in the dock wearing a dark suit, white shirt and blue tie as the sentence was handed down.
In mitigation, Neil Corre had urged the judge to suspend any custodial term because of Joyce’s efforts to battle his drink problem.
“This is an intelligent, healthy man who has served his country in the armed services and in Parliament,” he said.
“He understands that his previous offending was because he had a drink problem and it’s in my submission an indication of the strength of his character that he himself has overcome that drink problem through determination and willpower.”
Speaking after the hearing, Joyce said: “I think that is a fair outcome.”
Asked if he felt remorse, he added: “Of course.
“In the end it was a 14-year-old boy and that is a shame and a cause of considerable remorse and I have to both pay the price and make sure I don’t do it again.”