Gen Prawit said the plan to buy three submarines from China will not be on the cabinet's agenda until the Royal Thai Navy does a better job of raising awareness about why it needs them.
The navy should clearly explain to the people the benefits of having submarines to protect the national interest in territorial waters, he said.
The plan has received backing from Prime Minister Prayut Chan-o-ocha and from Gen Prawit, who is deputy prime minister in charge of security affairs.
But it also encountered fierce opposition, in particular criticism from the Pheu Thai Party and the People's Democratic Reform Committee, and social activists. They urged the government to use the money to help the country out of the economic slump and to recitify social problems, instead of buying new weapons.
The prime minister on Wednesday reiterated his support for the scheme, saying the navy had made a thorough study of the need to have submarines before it propose the procurement.
It had been planned to put the submarine project on the cabinet agenda on Tuesday.
The Type 039A submarine (NATO) reporting name Yuan-class diesel-electric submarine in China's People's Liberation Army Navy.