The group had attempted to hold a press conference on the opening of their anti-referendum fraud centre on June 5 last year, in a move deemed by the NCPO to have contravened the order.
Seventeen of the group were present in court, the absentees being Yossawarid Chooklom and Nisit Sinthuprai.
The court agreed to an appeal by their lawyers for testimony in the case to be postponed, and ordered them to appear in court again on September 5.