The demonstrators at Rebkong in east Tibet are mostly students and monks.
The protests coincide with a change in leaders at the top of China's government and involve criticism of Chinese reforms in the Tibetan education system, Voice of America reported Friday.
"Our sources have confirmed that many of the students [in the protests] have been calling for freedom of language and for the return of [the exiled Dalai Lama]," said Free Tibet Executive Director Stephanie Brigden.
Mass protests also took place in Rebkong in 2010, with demonstrators objecting to government plans to replace the Tibetan language with Chinese in local schools, Voice of America said.
There had been no government intervention but police and military units were deployed near government buildings where demonstrations occurred, the report said.