Kompany, the former City captain and centre-back, left for Anderlecht in the summer without replacement and the champions have since lost another key defender, Aymeric Laporte, with a long-term injury.
"I don't think they need to sign another defender," Kompany told Sky Sports after Sunday's defeat at Liverpool.
"We always struggle at Anfield. I said that on Super Sunday, you're fighting 25 years of not winning at Anfield and that's difficult, it's two games in one game - you're playing a great team and you're fighting history.
"Flip it around and the same will happen for Liverpool - they will fight the history of not winning the league for 30 years.
"That should be to City's advantage I still think. As to the defence, the best way for City to defend in the past has been to attack. They have no reason to change that.
"As soon as they start reconnecting with the best performances, I'm convinced that we can see a sustainable amount of wins."