In a strongly worded letter faxed to Thuli Madonsela on Monday, Mahlangu-Nkabinde said she was concerned that the provisional report was "made available to the media" before she could respond to the findings it contained.
The Public Protector had given her department until June 23 to respond.
Mahlangu-Nkabinde asked Madonsela to "seriously consider this matter as it is neither advisable nor acceptable to interact on the provisional report through the media".
The letter follows a Sunday Times report detailing the contents of the Public Protector's provisional report on the KwaZulu-Natal police headquarters property deal entered into with property mogul Roux Shabangu.
Titled "Against the Rules Too'', the report says that Mahlangu-Nkabinde is guilty of improper conduct for going ahead with the deal.
The report followed an earlier one in which the Public Protector described the R500-million lease agreement for the police's new Pretoria headquarters, also entered into between Public Works and Shabangu, as "invalid".
Public Protector CEO Themba Mthethwa said Madonsela was out of the country but Mahlangu-Nkabinde's concerns had been "brought to her attention".
Mahlangu-Nkabinde's spokesman, Sam Mkhwanazi, said he knew nothing about the letter.
Regarding the minister's announcement on Monday that she would ask a court to rule on the validity of the R500-million 10-year Pretoria lease deal, Mkhwanazi said Mahlangu-Nkabinde had "no opinion" on the outcome of the court application. He said the department's lawyers had yet to decide on a date on which to approach the court.
Shabangu refused to comment on Mahlangu-Nkabinde's decision to go to court for a review of the Middestad lease deal, saying: "Every time I talk to the media my words are twisted so I'm not going to say anything any more."
Tenants of the Middestad building are worried about what will happen to their businesses in the midst of the controversy surrounding the building.
Jacques Jansen van Rensburg, who runs a furniture shop in Middestad, said he had asked Shabangu about developments concerning the building, but had not been given a response.
He said he had heard that some of the tenants had been given notice to vacate the building.
"I don't know what's happening. I'm worried about my future here," he said.
Several offices and shops in the building are empty, testimony to the exodus of tenants.
Another tenant said law firms and other businesses occupying office space on the upper floors of the 18-storey building were being moved downstairs, and others were moving out completely.
"People are moving out and others are being relocated to the lower ground floor, usually occupied by shops," she said. - Additional reporting by Alfred Moselakgomo
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