The private Dogan news agency said police fired tear gas at the group in an area close to Prime Minister Recep Tayyip Erdogan's Istanbul offices on Monday. The protesters responded by hurling stones.
The agency said as many as 500 protesters were detained overnight Monday after police broke up a protests by several thousands of people in the capital Ankara. Turkey's Fox television reported 300 others detained in a similar crackdown in Izmir, Turkey's third largest city.
The demonstrations that grew out of anger over excessive police force have spiraled into Turkey's biggest anti-government demonstrations in years, challenging Erdogan's power.