Local officials in Lashio were cited by China's official Xinhua News Agency as saying at least 25 people were being questioned for their role in riots that left at least one person dead and five others injured.
All of those detained are from Lashio, though authorities said they were checking the city's gates to ensure that instigators hadn't come from surrounded areas.
A dusk-to-dawn curfew was imposed this week in response to the violence. Buddhists tried Thursday to tear down a home owned by Muslims, however.
More than a dozen shops and two mosques were set on fire during riots in Lashio this week. Riots were sparked Tuesday by the arrest of a man who allegedly set a gasoline vendor on fire.
Violence between Buddhists and Muslims has overshadowed political developments in Myanmar. Xinhua didn't report on the religious affiliation of the suspect or the vendor.
International sanctions pressure has eased on Myanmar in response to democratic reforms that began with general elections in 2010. Human rights groups have expressed concern that easing economic pressure could prompt Myanmar authorities to take security less seriously.