Warnock quit Bramall Lane after United were relegated on the final day of the Premier League campaign on goal difference as West Ham maintained their top flight status.
The Blades claimed an unfair punishment of a £5.5million fine was handed out to West Ham rather than a points deduction after they were found guilty regarding the ownership of Tevez and Javier Mascherano and Warnock remains unhappy that the Argentine striker was allowed to play for the Hammers in their final three games of the season.
"I am not blaming Tevez for our relegation. We all make mistakes and some of my decisions definitely cost us points," Warnock told The Sun.
"If we'd scored two more goals or played for a goalless draw at Aston Villa in our penultimate game we would have stayed up.
"But the fact is that everybody in football knows that Tevez is not owned by West Ham and never has been. He was illegally registered and should not have been allowed to play in the Premiership.
"And there's no way West Ham would have got out of it if Tevez had been banned, even if it was for just the final three games of the season. Not in a million years."
Warnock has given himself until Christmas to find himself a new job in football as he currently sits out his longest break from the game in 21 years.
"I've given myself until Christmas to find the right job," he continued.
"If it doesn't come up I'll move the family to Cornwall and work in the media full-time. I'll go on telly and slag people off with no comeback from the FA!
"I've made a few enemies over the years. Gary Megson, Stan Ternant, Wally Downes… but nowhere near as many as people might imagine after 38 years in the game."