About 100 of them held a symbolic protest at the intersection by holding banners against coup and shouting at troops, who were deployed to keep security there.
Hundreds of other people stood around the rally spot and on the skywalk and they joined in shouting at the troops, trying to pressure troops to leave the area.
At 12:30 pm, a woman, who wore a national flag symbol of the People's Democratic Reform Committee, walked past the protesters in front of McDonal Ratchaprasong, prompting the protesters to pelt her with things and water.
Officials rushed in to escort her from the rally scene.