Army chief Gen Apirat Kongsompng will not appear before the House committee on security matters and will instead send an assistant to testify and answer their questions.
The Royal Thai Army advised the committee of his intentions by letter on Monday.
The committee invited Gen Apirat to an exchange of opinions on security on Monday. The invitation followed Gen Apirat's special lecture on national security during which he accused some politicians and academics of still adhering to communist ideology, at army headquarters on Oct 11.
In response to the invitation that was sent to the defence minister, the army letter said such a discussion would create understanding between security authorities and the House committee, but Gen Apirat was not available to attend.
Instead, Gen Apirat had assigned assistant army chief Gen Sunai Praphuchanay to meet with the House committee.
Gen Sunai is a senior army officer, capable and experienced in the exchange of opinions, especially those concerning border and national reform issues, the letter said.
"The Royal Thai Army does hope that the House committee on national security will benefit from the discussion on security and honour the army delegation," it said.
Gen Apirat went to Kanchanaburi province on Monday morning to review the preparedness of a rapid deployment force.