The director, who has won an Oscar three times, said World Trade Centre, to be released this year around the fifth anniversary of the attacks, documented a day in the life of two men trapped at the scene, their rescuers and families.
Speaking to an audience during a question and answer session late Monday at the Bangkok International Film Festival, Stone was asked if Americans were ready for the first major Hollywood film on the subject.
"Is America ready for 9/11? Is America ready for gay sex? I don't know," Stone told the audience, referring to Ang Lee's Oscar-nominated Brokeback Mountain, which has been a surprise hit in US cinemas.
"It's about a rescue and families involved in the rescue. It's really a technical attempt to be realistic about what happened in that building," he said.
Nicolas Cage plays the film's lead role, New York Port Authority Sergeant John McLoughlin, who was trapped along with a fellow officer in the mangled wreckage of one of the twin towers that crumbled after being hit by hijacked passenger jets.
Besides the sensitivity of the subject matter to the American public, industry media have reported that some people linked to the Paramount Pictures project were concerned that Stone may introduce his own politics into the movie.
Bush has been criticised by Stone
for his handling of the 9/11 attacks
Stone has been publicly critical of President George Bush's handling of the attacks and their aftermath and in Bangkok told the audience that "the present administration has been a nightmare".
But Stone, whose film JFK was condemned in some quarters for pushing the argument that the 1963 assassination of president John F Kennedy was part of a plot, said there were no conspiracy theories in World Trade Centre.
"No, there's no mention of that because it's truly a 24-hour document of these men's lives," he said.
"They were right at the heart of the destruction ... right in the middle by an elevator shaft. They survived. It's about their rescue and their children at home," Stone said.