The 34-year-old actor spent four hours at a London police station before being released on bail.
A statement from Bale's London-based law firm Schillings said Bale denies the allegation.
"Christian Bale attended a London police station today on a voluntary basis. Bale, who denies the allegation, cooperated throughout, gave his account in full of the events in question, and has left the station without any charge being made against him by the police," it said.
British media had reported that Bale's mother and sister complained he had assaulted them at the Dorchester Hotel in London on Sunday night, a day before the European premiere of his latest film, "The Dark Knight."
The Sun newspaper said police did not question the actor Monday because they did not want to interfere with the premiere of the movie.
Asked Tuesday whether Bale had been arrested, a London police spokesman did not refer to him by name but said: "A 34-year-old man attended a central London police station this morning by appointment and was arrested in connection with an allegation of assault."
The spokesman spoke on condition of anonymity because force policy did not authorize him to be identified. British police do not name suspects before they are formally charged.
The force later said in a statement that the man had been released on bail pending further inquiries and told to return in September. It did not specify the date.
Bale's sister Sharon told reporters "it's a family matter" from her home in Corfe Mullen, 110 miles southwest of London.
A man who answered the door at the home of his mother, Jenny Bale, in nearby Bournemouth said she did not want to comment.
U.S.-based representatives for Bale didn't immediately return messages seeking comment. Repeated phone calls to Bale's London representative went unanswered.
Wales-born Bale first made a splash as the child star of Steven Spielberg's "Empire of the Sun" in 1987. His screen credits also include "American Psycho," "The Machinist" and "Batman Begins."
In "The Dark Knight," Bale reprises the role of wealthy playboy Bruce Wayne and his crime-fighting alter-ego Batman, a brooding vigilante superhero still scarred by the murder of his parents.
The Warner Bros. film, which stars the late Heath Ledger as Batman's nemesis The Joker, took in a record $158.4 million at the box office in its opening weekend in the U.S. last week.