Paulo Dybala scored twice, with Artem Dovbyk also on the scoresheet.
"I don’t know if it is the best Roma of the season, but I do know we have to improve,” Ranieri told DAZN.
“The lads had to cancel out the second half against Como, they did that and now we can have a nice Christmas, but after that we’ve got to do better because Roma have not won away from home in Serie A for eight months.
“It is not right that we have one Roma at home and one away, we need to wake up and do better.
“I always said Paulo (Dybala) plays when he is in shape. If he seems tired or that the game needs something else, I will take him off. Jose Mourinho said it and so will I, there is one Roma with Dybala and one without.”
On Mats Hummels and Leandro Paredes, he also said: “What can I say? Hummels is a World Cup winner, he played a Champions League Final. He had flu all week and barely trained, but when he says that he can play, then I play him.
“Paredes is the same, an incredible playmaker who needs only one or two touches. These are the players I like, they have experience and can dictate the tempo.”