Anthony Joshua threatened to throw a chair across the face of Daniel Dubois as the two heavyweights were restrained by security during a heated interview.
Dubois, 26, will defend the IBF world title against his fellow Briton at Wembley Stadium on 21 September.
Broadcaster Dazn released a short clip of the interview, recorded before Thursday’s news conference, on social media.
Two-time world champion Joshua, 34, said he was “ready to fight”, to which Dubois replied: “Let’s go. If he wants to swing, let’s go now.”
A visibly annoyed Joshua told Dubois not to disrespect him, adding: “I’ll throw this [expletive] chair across your face.”