This came after Gen Prayut earlier blamed rice mill operators and some local politicians for manipulating rice prices and causing the price plunge.
Gen Prayut said he did not want the executives to step down because it would take time to appoint new ones.
The government sometimes obtains information and needs the association to explain the facts, the premier added.
Government spokesman Sansern Kaewkamnerd said Ms Yingluck's buying rice from farmers in the Northeast would be accepted by society if she was willing to help farmers without a hidden agenda and was not attempting to seek a political boost.