Wallop said various activities had been detected, including from active politicians and people who had “lost benefits”.
He added that he could not confirm if such activities were strong enough to topple the government.
The NSC would monitor the trend to ensure social order was maintained, he said.
Prime Minister General Prayut Chan-o-cha on Tuesday accused the media and politicians of attempting to overthrow the junta government and the National Council for Peace and Order in a letter delivered to Cabinet members.
Wallop said the premier had not specially instructed security officers to deal with the issue.