Ranieri's men have made an unbeaten start to the campaign and sit top of Ligue 1 having won four of their five opening matches, but face their sternest test yet when they travel to the Parc des Princes on Sunday.
The newly-promoted club spent heavily during the close-season and the arrival of Falcao, Joao Moutinho and James Rodriguez have raised expectations of a title challenge.
However, Ranieri has sought to take the pressure off his side by claiming PSG - who are also undefeated, but sit two points behind his men in the table - need a victory more than Monaco.
"Winning the game is more important for PSG than for us," the 61-year-old said. "The players are very motivated for this game, for us it will be a good test.
"I do not think PSG will suffer after their match in the Uefa Champions League, this is only the beginning of the season."
The Italian then warned the Ligue 1 champions that star striker Falcao - who moved to the club in a €60 million deal from Atletico Madrid over the summer - has still not hit top form, despite scoring four goals already.
"Falcao is not 100 per cent yet but has a fantastic mentality," the Italian added. "We expect a lot from him, that is normal because he is one of the best strikers in the world."