Lungisa made the statement during a debate on the nationalisation of the Reserve Bank where Kganyago described attacks on the central bank as the arrival of the "barbarians at the gate of SARB".
Kyanyago’s attorney wrote that his client's reputation had been damaged to the tune of R500,000.
On Tuesday, Lungisa said the move by Kganyago was an attack and that he would challenge it.
Lungisa said: "We were called barbarians at the gate. We are going to challenge this. There is no other way, the revolution must be defended at all cost.
"Lesetja [Kganyago] called us barbarians at the gate but today he takes refuge in our cause when we return insults with fact. I have simply returned insults with facts," Lungisa said.