Nowak was told in Johannesburg in neighbouring South Africa that his visit had been postponed due to talks between mediators from the 15-nation South African Development Community (Sadc) and leaders of the Zimbabwean power-sharing government.
"This was a calculated move to create a diplomatic incident"
Simbarashe Mumbengegwi, Zimbabwe's foreign minister
"This was a calculated move to create a diplomatic incident," Mumbengegwi said.
Mumbengegwi is a close ally of Mugabe and the foreign office is controlled by Zanu-PF loyalists under the agreement that divided the ministries between the Zimbabwean rivals.
Nowak called for the UN Human Rights Council to act after he was deported back to South Africa just hours after arriving in the country, but acknowledged that immediate moves were unlikely.
"I think it sheds light on the present power structure of the unity government if the prime minister invites me for a personal meeting and his office is not in a position to clear my entrance to the country," Nowak said.
"That is a very alarming signal about the power structure of the present government."
Nowak said that options open to the council included the adoption of a resolution condemning Zimbabwe and requesting an investigation, or it could set up an independent investigation team to look into human rights in the country.
But Mumbengegwi said that Nowak's comments about a disfunctional government reflected his political views.