Ranieri, who guided his side into France's top division last season, has already acquired seven new signings this summer.
However, the former Chelsea boss believes that "the team is still missing something".
"The club's objective is to finish in the top three, but the team is still missing something," he told the Il Corriere dello Sport.
"We are missing some players of substance who would really add something to the team. The squad has already changed a lot compared to last year and has become very strong, but we are not complete yet.
"We are still far away from PSG's level, although I understand that the people will see Ligue 1 as a battle between us and them. We have an ambitious president and a lot of money."