In his reply to her report, Zuma indicated Police Minister Nathi Nhleko needed to determine if he should pay back any of the R246 million spent on security upgrades at his Nkandla, KwaZulu-Natal, homestead.
"I am concerned that the decision you have made regarding the police minister gives him power he does not have under law, which is to review my decision taken in pursuit of the powers of administrative scrutiny I am given... by the Constitution," she wrote in a letter to Zuma.
"As I have already indicated, reports of the public protector are by law not subject to any review or second-guessing by a minister and/or the Cabinet."
Her findings and remedial action could only be set aside by a court of law, she wrote.
She noted that in his 20-page reply to her report he did not address her findings or remedial action.
In her report, titled "Secure in Comfort", Madonsela indicated Zuma needed to repay all non-security related expenses at Nkandla, such as the swimming pool, cattle kraal, amphitheatre, and vistors' centre.