2:45 PM PT -- Dana White says the decision to move UFC 232 from Las Vegas to Los Angeles cost roughly $6 million.

White says he did NOT want to cancel the fight and worked to find a venue where it could happen when problems arose in Nevada.

White says once they found out The Forum in L.A. was available, they booked it and the rest is history.

Alexander Gustafsson just went off on Jon Jones to his face -- saying the guy is a "terrible" cheater who's spewing "bullsh*t" about his positive PED test.

The two exchanged shots at the UFC 232 press conference -- Gustafsson says he's convinced Jones is a cheater, but didn't want to back out of the Dec. 29 fight because he wants to beat the guy's ass.

"I'm here to fight," Gustafsson said ... "He will eat it Saturday night."

UFC 232 was supposed to go down in Las Vegas -- but was moved to L.A. after Jones tested positive for Turinabol, an anabolic steroid.

Jones has insisted he only had trace amounts of the PED in his system -- remnants of the last time he tested positive. He's adamant the Turinabol in his system is not new.

The UFC -- along with the California State Athletic Commission and other officials -- believe Jones, which is why the fight was greenlit in CA.

During the event, Jones doubled down on his claim that he's not a cheater and will eventually be vindicated by tested organizations.

Jones says it's "hilarious" that people think PEDs are the reason for his success.