The James Bond actor - who plays journalist Mikael Blomkvist in the remake of the film, which is based on the book of the same name by Stieg Larsson - admitted he had to put his hand over his mouth because he was so shocked at the content of the motion picture after being shown a cut by director David Fincher.
He said: "It's as adult as you can possibly make it. This is adult drama. I grew up, as we f**king all did, watching 'The Godfather' and that, movies that were made for adults.
"And this is a $100 million R-rated movie. Nobody makes those anymore. And Fincher, he's not holding back. They've given him free rein. He showed me some scenes recently, and my hand was over my mouth, going, 'Are you f*****g serious?' "
Daniel revealed there is some "horribly graphic" footage in the adaptation of the novel, which contains torture chambers and people being lit on fire.
He told Esquire magazine: "It's not that he simply showed me footage that was horribly graphic. It was stuff that was happening, or had happened. And somehow you don't see it."
The English-language thriller - the second film based on the novel - features Mikael investigating the disappearance of a young woman with help from Lisbeth Salander (Rooney Mara).
The movie is set to be released in December.