Malcolm Shabazz, 29, died in a hospital from multiple injuries, The New York Times reported Friday.
Miguel Suarez, a union activist traveling with Shabazz, said he and Shabazz had been invited to a bar at Plaza Garibaldi, a popular tourist area, by a woman Wednesday night. A fight broke out when the bar owner demanded they pay $1,200 for drinks and female companionship, he said.
Suarez said he escaped but returned later to find Shabazz seriously injured outside the bar early Thursday.
The Mexican attorney general said he was investigating the death.
Shabazz was the son of Qubilah Shabazz, one of Malcolm X's six daughters.
He served time in a juvenile facility when he started a fire at age 12 that killed his grandmother, Betty Shabazz, Malcolm X's widow, the BBC reported.
Shabazz was in and out of prison in later years for other crimes.
He called himself "the first male to Malcolm X" on his website. Since his release from prison, Shabazz said he had been speaking to people around the world "about the struggles that confront this generation."