"Everybody is always asking why this custody battle has been going on for so many years, and now they have the answer," Basinger's publicist, Annett Wolf, read from a statement. "The issue is not about Kim or the alleged alienation that Alec constantly refers to; it is about his ongoing aggressive behavior."
The couple divorced in 2001 and share custody of 11-year-old Ireland, who lives in Los Angeles with Basinger. Baldwin lives in New York.
Basinger said she hired security personnel after the media frenzy that followed the message's release "to allow Ireland to maintain her regular routine," the Los Angeles Times reported Monday on its Web site.
In a closed hearing, a family court judge heard the message and barred Baldwin from contacting the girl; the message in which he cursed and called her names was part of the proceeding.
Baldwin's attorney filed a request in court to learn who leaked the message.
A May 4 hearing on Baldwin's visitation rights was scheduled.