A 35-year-old man was on Thursday sentenced to seven months in prison over his participation in a lunchtime anti-government protest in Central.

Cheung Chin-man earlier pleaded guilty at Eastern Magistracy to assaulting a police officer, and was convicted after trial of taking part in an unlawful assembly and using a facial covering in violation of the mask ban imposed by the government.

The court heard that on November 13, 2019, Cheung dashed towards a police sergeant as officers were dispersing a group of black-clad protesters on the podium at Exchange Square.

Riot officers at the scene believed he was trying to attack the sergeant and so they subdued him.

In mitigation, the defence lawyer said Cheung had not planned to join the protest, but had acted on impulse.

The lawyer also noted that Cheung did not throw things at officers like other people did, and there was no evidence to suggest he had hurt anyone or damaged anything.

The counsel urged the court to try to understand how the social unrest had affected people's emotions and their daily lives.

But in passing sentence, magistrate David Cheung said the protest took place during the lunch hour, posing a great threat to the public and breaching the peace.

He said those who act on impulse should not be tolerated.

The magistrate added that although the sergeant was not injured, Cheung's act was still a serious crime.