Surveillance video showed a fire erupting at Los Perros in Tamiami early Wednesday.
Ten Miami-Dade Fire Rescue units were called to 13350 SW 42nd Street just after 6 a.m.
Video showed the flames shoot into the air before smoke filled the screen.
"It's a big loss. It's a big loss. Everybody is sad," said Los Perros owner Ron Luna. "I couldn't believe it. This has never happened. Accidents happen."
Investigators blamed rainwater hitting faulty wiring on the restaurant's sign for sparking the fire.
Luna said they would clean up, then reopen.