Thirlby discussed the film while appearing to promote upcoming comic book adaptation Dredd, where she appears as Judge Anderson.
Speaking to The Hollywood Reporter, the 25-year-old actress claimed that the film is not a traditional biopic, saying: "I would hate to call it straightforward.
"But it will be an artistic film that does justice hopefully to a true artist – someone who truly gave something to the world."
Thirlby added: "I think that the goal for it is to be able to somewhat match the artistry of the music itself, hopefully."
Buckley accidentally drowned in the Mississippi River in May 1997 aged 30, after releasing only one complete studio album, the classic Grace.
His music has since achieved legendary status, with Buckley's cover of Leonard Cohen's 'Hallelujah' appearing in a number of adverts, films and television programmes. The track also re-entered the UK charts - alongside X Factor winner Alexandra Burke's cover of the same song - in December 2008.
Watch the video for Jeff Buckley's 'Everybody Here Wants You' below: