"This is a squad of champions," Ranieri said in his first news conference, a day after being appointed to replace the sacked Gian Piero Gasperini.
"I want to see the Inter that I confronted when I was Roma coach," Ranieri added. "A year-and-a-half ago these boys were champions and I believe in their ability to come back from adversity.
"I don't think Inter's players are worn out or finished," said Ranieri, who is Inter's fourth coach since Jose Mourinho led the Nerazzurri to the Champions League title 16 months ago.
"There have been injuries and bad luck but now we need to restore confidence by taking points.
"We've tripped up but now we need to get up and fight from the first to the last. I want to see that never-say-die, tight-knit group again. We need to win because the players are used to it."
Gasperini was sacked after three months in charge following a poor start to the season in which Inter, Serie A champions from 2006-2010, lost four and drew one of their opening five matches.
Last season Leonardo took Inter to the runners-up spot after Rafa Benitez had departed in December following a string of poor results.
ONE POINT
The 59-year-old Ranieri, who has coached 12 teams in three countries in his 24-year career, admitted he had come to be seen as a person who could fix teams in crisis.
"Everyone has their own karma; mine is obviously fixer," said Ranieri, who came close to winning the title with Roma in 2010 after taking over from Luciano Spalletti at a similar stage in the season.
"I'm happy to be here, even though it was a surprise as I had been thinking about coaching abroad."
Inter have been beaten by city rivals AC Milan in the Italian Super Cup, defeated at home by Trabzonspor in their opening Champions League fixture and picked up just one point from their opening three Serie A matches this season.
Ranieri said they could still compete on all fronts.
"The results of the other clubs have gone our way," he said, referring to Milan's and Roma's winless start. "It's now up to us to get back among the pack. We are low in the table but the others are not too many points away."
The Italian, who will be without playmaker Wesley Sneijder because of a muscle injury and defender Andrea Ranocchia through suspension for Saturday's match at Bologna, said he would not tinker with the side's formation.
"I'm not a slave to any formation," he said. "I play to win and that's all. [Giampaolo] Pazzini and [Diego] Milito can play together as they both have good movement and are poachers in the box.
"We need to improve our crossing. The area counts a lot in football but it's mostly about common sense. Every club has good and bad points. I have to show up the good things and hide the defects."
Despite a pedigree that includes stints at Napoli, Fiorentina, Valencia, Atletico Madrid, Chelsea, Juventus and Roma, Ranieri has never won a league title. He won the Copa del Rey with Valencia in 1999 and the Coppa Itali
