A former champion boxer who bashed a police officer with a pole during a riot in Sydney has been jailed.

Ahmed Elomar, 32, pleaded guilty to hitting the officer over the head with a flag pole, knocking him unconscious, during riots over the film Innocence of Muslims in September 2012.

The male officer needed stitches.

Judge Donna Woodburn told Sydney's Downing Centre District Court it was a cowardly act as the officer had already been punched and was vulnerable.

She said Anthony Mundine provided a reference for Elomar saying he was an honest, hard working man and who understood he had done the wrong thing.

Riot police arrive at a Sydney protest in September 2012, over the film Innocence of Muslims, which ridicules the Islamic Prophet Mohammad. ( Josh Bavas )

Elomar was sentenced to four years and eight months in jail and must serve at least two and a half years of the sentence.

Judge Woodburn said she took into account his plea of guilty, his remorse and an intellectual disability.

His brother, Mohamed Elomar, is believed to be fighting in Syria, and his uncle, who is also named Mohamed, was one of 18 people sentenced over a terrorist plot to blow up targets in Melbourne and Sydney.