The film, which is being shown in two parts, is a drama about a woman's erotic journey from birth to the age of 50. LaBeouf plays Jerome - one of the leads in Lars Con Trier's controversial film.
Also in attendance at the press conference was Uma Thurman, Stellan Skarsgard and Stacy Martin.
The film's controversial director, Von Trier, did not attend despite being seen at the festival earlier.
In his absence though, those in attendance showered the Danish director with praise.
Thurman said working with Von Trier was "unbelievably refreshing."
