Filmmaker Eric Khoo said at a press conference on Tuesday that the Media Development Authority (MDA) had chosen not to classify his film, In The Room, for commercial release, according to local newspaper The Straits Times.
The MDA had given the film, without cuts, an R21 rating for its screening at the Singapore International Film Festival.
Film festivals in Singapore are generally allowed more leeway than commercial releases.
It is due for commercial release in Hong Kong in January, where it is rated for people aged 18 and over.
In The Room takes place in a fictional hotel in Singapore, and contains references to the island's cultural and political history.
It takes inspiration from 1970s soft-core erotic films such as The Story of O and the French Emmanuelle series.
The MDA did not respond to inquiries about whether or not the film had received a classification, although it was not listed on the organisation's movie database.
Khoo, who said there was "nothing contentious" about the film, intended to appeal the MDA's decision, the Straits Times reported.
The MDA has been known to restrict the reach of works which it deems problematic or objectionable.
In 2014, it also refused to rate the documentary film To Singapore, With Love, arguing that the film would pose a "serious risk to Singapore's national security."
The government body last week however lifted bans on 240 publications, ranging from anti-colonialist periodicals to adult magazines and erotic fiction.
Only 17 titles remain banned, adult magazines Playboy, Penthouse and Hustler among them.
Publications by the Jehovah's Witness group also remain banned.
Films that have been banned in Singapore include Monty Python's Life of Brian and Zoolander.