EXCLUSIVE

Asia Argento's attorney fired off a stern warning to Jimmy Bennett -- be very careful with what you say about me ... or you're gonna regret it.

Asia's attorney, Mark Heller, fired off a letter to Jimmy's lawyer Thursday -- obtained by TMZ -- regarding the reported upcoming interview he's got scheduled on an Italian television station to address their sexual encounter on May 9, 2013.

According to the letter ... Bennett's words will be carefully monitored for any "slanderous, defamatory or untruthful statements" concerning Argento, and if they believe there are any -- they'll be taking legal action.

Jimmy's interview is scheduled for sometime this weekend. As you know, Asia is originally from Italy and has a home there.

As we've reported ... both Argento and Bennett have made sexual assault allegations against each other. The two had sex in a Marina del Rey, CA hotel room when he was just 17. She says he was a horny kid who pounced on her and took away her free will. He says this was planned seduction with a minor.

The photo of Argento and Bennett in bed after they had sex, along with the text messages, seem to support Bennett's version.

Argento trashed Bennett, calling him a failed actor and drug abuser.