The United States has imposed new sanctions on North Korea as part of its first response to the cyber attack on Sony Pictures.
The FBI has blamed North Korea for the attack which leaked confidential data from Sony computers.
North Korea has denied the allegation but expressed fury over Sony's comedy The Interview, which features a plot to assassinate leader Kim Jong Un.
The online warning against filmgoers who see Seth Rogen and James Franco's upcoming Sony film The Interview was purportedly posted by 'Guardians of Peace' hackers.
The warning, written in broken English, hints at a September 11-style attack and recommends "to keep yourself distant" from the places showing the film.
North Korea's dispute with the US over computer hacking took a new twist when the communist state lost Internet access for several hours.
A hacker group who claimed to be behind a cyber attack on Sony Pictures have posted a message online apparently mocking the FBI.
Events company Secret Cinema is planning to screen a film in protest at what they have called the 'censorship' of The Interview.