Police issued the clarification on Monday after a Facebook page "Phra Chan Lai Kratai" (rabbit pattern moon) posted a picture of some police officers standing outside the police station in the heat without their shirt and shoes.
The incident took place on Saturday, the page said, claiming that some officers had suffered from heatstroke or sunburn.
According to the letter from police station superintendent Pol Colonel Prachya Paite, 14 police officers were punished to undergo discipline training for failure in performing duties.
It said some police officers had neglected their duties to receive complaints and coordinate in the legal process, increasing the workload on other officers.
The officers had failed to input information into the police's crime system as well, the letter said, adding that the police chief had instructed them to be responsible in their work many times.
Prachya said the discipline training aimed to make the police officers conscious of their duties, adding that no physical contact was made during the training.
Pol Sgt-Major Adisorn Suknual, commander of crime prevention and suppression division, who was among the 14 police officers punished, said they were ordered to switch positions between standing and resting every few hours.
He denied that anybody had suffered a heatstroke, adding that some officers who were unable to stand had been allowed to sit for a while.