Tyson charged the WBC and IBF heavyweight champion right after the start of a conference called to announce their April 6 bout, and a brawl broke out on stage at the Hudson Theater.
Neither fighter hit the other, but Tyson had a cut on his hairline after the swarm of bodies was pulled apart.
WBC president Jose Sulaiman was knocked down during the melee.
The news conference for Lewis' defense of his two belts against Tyson in the MGM Grand in Las Vegas was called off.
Lewis was supposed to meet reporters later Tuesday, but instead business agent Adrian Ogun read a statement from the champion.
"As a result of today's event, I will evaluate my options after the relative boxing commissions have ruled," Lewis said.
The fight must be licensed by the Nevada State Athletic Commission, which fined Tyson $3 million and revoked his license for a year after he bit Evander Holyfield's ears in 1997.
Tuesday's fracas recalled the scene when Lewis and Hasim Rahman exchanged words and chest bumps before wrestling on the floor during a TV interview in August. That was 2½ months before Lewis knocked out Rahman in a rematch to regain the heavyweight title.
On Tuesday, after video highlights of the two fighters' careers were shown, Tyson was introduced first.
He walked onstage dressed entirely in black, then faced the wing of the stage from which Lewis was to enter. When Lewis, dressed in a gray suit, stepped onto the stage, Tyson rushed him.
People jumped in to keep them apart and it appeared at least one person was hit by a punch. Then, for several minutes, bodies were rolling around and throwing punches until order was restored.
Tyson then strode to the front of the stage, threw his arms into the air in a triumphant stance and made an obscene gesture.
Someone in the audience shouted, "Put him in a straitjacket!"
The former undisputed heavyweight champion screamed an obscenity at the man and said, "You're scared of a real man."
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