Police pushed back pro-democracy supporters who had gathered at the Din Daeng police station in Bangkok on Friday to hold a candlelit vigil for a young protester who died a day earlier.
The 15-year-old boy had been in a coma since August, caused by a gunshot wound that left a bullet lodged close to his brain.
Around 50 police holding riot shields cleared out about 100 protesters who had gathered at the station, where activists had gathered to lay flowers and candles on Friday.
The Din Daeng intersection has become a flashpoint between protesters and security forces. Clashes have often resulted in violence, with protesters throwing rocks, and police using water cannons and firing rubber bullets.
Police have said they do not use real guns. The shooting of the teenager is still being investigated.
Demonstrations against the government of Prime Minister Prayut Chan-o-cha have escalated in recent weeks over his management of the coronavirus and the economy.
Pro-democracy demonstrators plan another gathering this weekend, ahead of the reopening of the country to vaccinated tourists form 46 countries starting on Monday.
"Those who have come out to create violence, please don't do that,” Gen Prayut said on Friday. "Tourists will be worried and won't come.
"These images go to other countries".
The government on Friday issued a fresh order banning rallies and activities that risk spreading Covid-19 in 17 provinces that will reopen to international travellers.