About 100 demonstrators were detained at an energy ministry complex on charges of violating a state of emergency, National Security Council chief Paradorn Pattanatabut told AFP.
"There was no resistance," he said. "They were overwhelmed by the police forces."
It is the first time such a large number of protesters have been arrested since mass rallies seeking to overthrow Prime Minister Yingluck Shinawatra began more than three months ago.