The incident apparently took place on Sunday at a local hotel.
The alleged victim, who calls herself Gah-bee on Twitter, was apparently found in the company of Mugabe’s two sons in a hotel room before she was attacked.
The woman took to Twitter to tell about her ordeal.
She claims that Mugabe used an extension cord to attack her and her two friends and that she suffered gashes to her head.
Mugabe was in South Africa to receive medical treatment after she injured her foot.
Zimbabwe’s ruling party, Zanu-PF on Twitter confirmed an incident had occurred but said the Zimbabwean first lady was not to blame.