A protest involving about 200 people took place in central Bangkok on Tuesday evening, with participants demanding the resignation of Prime Minister Prayuth Chan-ocha.
Anti-government activists insist that Prayuth holds the post illegitimately because he seized power through a coup that ousted an elected government in 2014.
Videos from the protest were shared online.
68-year-old Prayuth was an army chief when he led a coup in 2014 to topple an elected government. In 2019, after an election was held in line with a military-drafted constitution, he became a civilian prime minister.
Thailand's main opposition Pheu Thai Party, as well as about two-thirds of the population, according to a recent opinion poll, believe the prime minister should step down by August 24 because his time as junta chief counts towards his term in office.
This comes as the Constitutional Court considers whether to take up a petition to rule on when the prime minister's constitutionally stipulated eight-year term expires. The court's decision on either to hear or dismiss the case is due on Wednesday.