The violence, in which 30 people were arrested, came amid a surge in protests in recent weeks because of increasing economic hardship and alleged mismanagement by the government of President Robert Mugabe.
An Associated Press journalist saw protesters severely beat two police officers with sticks, then take their uniforms and helmets and wear them.
The protesters blocked roads leading into the center of Harare, forcing many people to walk up to 6 miles (10 kilometers) to get to work. Rioters threw stones at police and vehicles, and some children on their way to school were caught up in the chaos.
Some police were seen firing live ammunition into the air to ward off the crowds. They also brought in police dogs. The drivers' grievances stem from anger over numerous roadblocks that police sometimes set up in city streets, which drivers allege are to demand bribes. Police said they had reduced the number of roadblocks after complaints from parliamentarians, tourism operators and others.
"We have information and intelligence on the identities of some criminal elements who are behind the social unrest," Charamba said at a news conference.
Such acts of defiance and clashes with the police are rare in Zimbabwe, although the government deployed the army against 1998 riots over soaring food prices. Mugabe, 92, has ruled the southern African country since independence from white minority rule in 1980, scoffing at frequent allegations of human rights violations.
Frustrations over rapidly deteriorating economic conditions in Zimbabwe, compounded by dissatisfaction over alleged government corruption and incompetence, have resulted in near-daily protests in recent weeks.
