Wan Ubumrung apologised to the prime minister and all the top brass on Wednesday after sharply criticising the regime on social media.
Mr Wan went to the government complaint centre opposite Government House with a garland to show his remorse to Prayut Chan-o-cha and National Council for Peace and Order (NCPO) members.
The son of Pheu Thai key figure Chalerm Ubumrung did not meet the prime minister. Sompas Nilaphan, a deputy permanent secretary for the Prime Minister's Office, accepted the flowers on his behalf.
Mr Wan, who unsuccessfully ran for Bangkok MP under the Pheu Thai banner, used his Facebook account on Tuesday to attack the generals with abusive language.
"All generals go to hell" because they have moved the country backwards, he wrote.
Instead of going to hell, First Army Region commander Lt Gen Apirat Kongsompong ordered Mr Wan to report to the barracks on Wednesday.
The attacking message was removed from Mr Wan's account on Wednesday, and replaced by one of an entirely different tone.
"I have checked my previous message and found that it was not right and is causing damage to the NCPO and government executives," he wrote.
"I hope you forgive me for this mistake."
Mr Wan said at the centre that he had the courage to accept responsibility for his mistake but refused to give reporters any details of his meeting with Lt Gen Apirat.
Mr Wan joined other politicians and critics who opposed the prime minister's plan to ask four questions. Critics deemed them "leading questions" designed to help him hang on to power and delay elections.