Reports had suggested Zingarevich was planning to bring in Dick Advocaat as the new coach and had already lined up a host of new signings not approved by the current boss.
But following Reading's 2-1 win over Everton, the 30-year-old insists the speculation is completely unfounded.
"The speculation hurts me because it's just not necessary," said Zingarevich, in comments reported by the Daily Telegraph.
"It is just nonsense really. I have total faith in McDermott and he has a long-term contract so I don't see any problem.
"There will be funds available. There will be a list at some point and we will discuss it. But the manager is the manager. He will make the final decision on all transfers.
"I don't even know where that Dick Advocaat speculation came from. Of course Brian was hurt by it. But he knows from me - because we talk - that everything is fine."
The triumph over the Toffees was Reading's first of the season but Zingarevich was full of praise for McDermott despite the Royals only being kept out of the drop zone on goal difference.
"You can be a good coach without being the right manager - but he really is," he added. "To be a good manager, you have to be a good psychologist and I really think he is."
Zingarevich is believed to have been instrumental in bringing Russian striker Pavel Pogrebnyak to the club in the summer and was believed to be pushing to bring Andrey Arshavin to Reading.
But the owner played down his remarks, saying: "When asked about Arshavin, I said he's a good player. I never actually said that we are interested in signing him. It was in the Russian news. Basically, it was mistranslated."