But the promised crackdown never came despite the passing of two deadlines for the protesters to disperse.
"We will not be using force as long as the protesters remain peaceful and they conduct themselves within the law," Chalerm Yoobamrung, the interior minister, said later in the day.
Asawin Kwanmuang, Bangkok's metropolitan police chief, said police would "use soft means to persuade protesters to get off the street".
Al Jazeera's Selina Downes, reporting from Bangkok, said that the protesters, led by the opposition People's Alliance Democracy (PAD), accuse the government of being a front for Thaksin Shinawatra, the ousted former premier.
Somkiat Pongpaiboon, a protest leader, vowed that the group would continue to demonstrate peacefully until the government is toppled.
"But if they hurt us or violate our rights, we will defend ourselves," he said to a crowd of cheering protesters.
Some of the activists wore helmets and masks, apparently to protect themselves if force was used, while others armed themselves with wooden sticks and makeshift shields.