Arrest warrants were issued on Thursday for two activists suspected of intending to harm Her Majesty the Queen's liberty during a rally on Wednesday.
If found guilty, the pair could be jailed for 16 years to life.
The warrants identified the two as Ekkachai Hongkangwan and Bunkueanun Paothon, political activists present at the rally.
The court granted the warrants following a request by Dusit police over an incident about 5.30pm on Wednesday on Phitsanulok Road.
On that day, the royal motorcade of Her Majesty the Queen passed along the road, which was cordoned off by security officers to stop protesters.
However, many protesters got through, and many were seen flashing the three-finger salute as her motorcade passed.
Her Majesty, representing His Majesty the King, was accompanied by His Royal Highness Prince Dipangkorn Rasmijoti.
She was to offer robes to monks as part of a ceremony at two temples.
Meanwhile, protest leaders Arnon Nampa and Prasit Khrutharoj were arrested in Bangkok and sent to Chiang Mai, where the provincial court issued arrest warrants for them.
Before he was arrested, Mr Arnon accused the police of using questionable tactics by leading the Queen's motorcade into the protest area. He said police wanted to show protesters as users of violence.
Although the allegations were unclear, three senior police were abruptly transferred.
