United have slipped six points behind neighbours Manchester City after losing two of their first five Premier League games.
He said: "I always said since day one that my title ambitions were also a motivational factor, also a way of living.
"I don't understand how you can be in this club and give a different message, but I knew - and I admit I knew it immediately - that was a very risky approach.
"If you remember my words, I said something like I am not playing defensively with my words because I know that it is difficult.
"We are playing against good teams. Every team is good, many of the teams are stable, many of the teams have stability from years of the same manager, others with stability with the same players. Others also with important investment so this is the Premier League and I think that's why people love the Premier League."