Four thousand soldiers and 2,000 police officers will be deployed to prevent any "flash mobs" from forming at five locations: Victory Monument, Siam Paragon, Suvarnabhumi Airport, Amarin Plaza at the Ratchaprasong intersection, and the Temple of the Emerald Buddha.
Previous anti-coup protests have been organised at short notice through social media, with locations not known until shortly before crowds started to gather.
In the days immediately following the May 22 coup, small groups gathered at Victory Monument and authorities responded by sealing off all roads to the area and closing BTS stations to deter activity.
Officers will also be stationed on Sunday at department stores along the routes of the BTS train system, deputy police chief Somyot Poompanmoung said after a meeting between police and military leaders.
Traffic in the vicinity of the potential rally sites will not be blocked but security authorities will operate checkpoints to screen passers-by.
Police and soldiers will also be deployed on the BTS train system and authorities will examine surveillance camera footage of the elevated train system if they need to seek warrants for the arrest of demonstrators.
Pol Gen Somyot also said that apart from the soldiers and police, rapid movement units would be deployed to handle demonstrators. He said authorities would avoid confrontations that might lead to clashes. In dealing with any demonstrations that might arise, officers would begin with soft actions but could proceed to harsher measures authorised by law if necessary, he sdded.
The deputy police chief also said that the military would be the lead body in dealing with any demonstrators, and police would play supporting roles.
He added that authorities were also checking if any foreign news agencies were directed to intentionally exaggerate reports and pictures of confrontations between demonstrators and police and soldiers in the way that affected the image of Thailand.