Warnock had been keen to take the former Blackpool striker to Bramall Lane but he says that after talking to Saints boss Steve Wigley that the striker is set to sign a loan deal with Kevin Blackwell's side.
"Steve (Wigley) told me that Ormerod was going to Leeds and I am very disappointed," Warnock told his clubs official website.
"Perhaps I should have talked to the player first but it's a lesson for me even at this stage of my career. Perhaps I shouldn't do things legally."