The blaze broke out in a function room at the 221-room Grand Park Avenue Hotel off the Sukhumvit Road in the Thai capital on Thursday evening.
Two Russian tourists died and about 20 people suffered smoke inhalation.
The Bangkok Metropolitan Administration will file a complaint for police to take action against the hotel, said Viparat Chaiyanukit, chief of Klong Toey district where the hotel is located.
"Legal action will be taken against the hotel for violating construction laws," Viparat told AFP.
Viparat said she could not provide details but reports said the hotel had requested permission to renovate car parks but instead constructed ballrooms.
If found guilty, the hotel owner could face three months in jail or a 60,000 baht ($2,000) fine.
Thailand is a tourist magnet but its image as the "Land of Smiles" has been tested in recent years by deadly political unrest, devastating floods and more recently a bungled bomb plot involving Iranian suspects.