"We will hit the people who, directly and indirectly, played a role in the martyrdom of the great man [Soleimani]," IRGC Commander Hossein Salami said in a ceremony addressing military commanders and staff as Tasnim News Agency reported on Sunday.
The IRGC commander said that any revenge for Soleimani would be taken in an "honorable, fair and just manner, not on a female ambassador to South Africa."
"If a hair is missing from an Iranian, we will burn all of your hair. These threats are serious. We won't do verbal fights. We will leave everything to the field of action. We will go on, with confidence and strength," he added.
Iran had dismissed the plot about killing the U.S. diplomat in South African right after accusations were made when Politico published a report on Sept. 13 about an alleged Iranian plot to assassinate Lana Marks, a longtime friend of Trump who began her work as an ambassador to South Africa in October.
The IRGC commander made the revenge statements after South Africa's State Security Agency said it had found no evidence to support the reports on the Iranian plot.
"At present, the information provided is not sufficient to sustain the allegation that there is a credible threat against the United States ambassador to South Africa," State Security Agency spokesperson Mava Scott said in a statement, adding that South African officials had met with their U.S. counterparts to request additional information.