The Foxes extended their lead at the top of the table with a convincing win thanks to two goals from Robert Huth and a Riyad Mahrez strike.
Leicester are now five points ahead of second-placed Tottenham and six clear of City and Ranieri was delighted with his side's display.
"It was a good performance for us, difficult because when you play against a team like City with players of fantastic quality it is not easy," Ranieri told reporters.
"But we were very, very concentrated. We want to try to win without pressure, just enjoy the match and try to do our best.
"The first goal was very good for our confidence and then we closed all the space because we played in a very concentrated and determined way through all the match.
"I said from the first moment here at Leicester there is a fantastic dressing room.
"On the pitch they help each other, they fight for each other and that is fantastic spirit.
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"We are 11 on the pitch and that is important. We play every time with 11. It is not easy.
"It is the best spirit I remember in my career, as well when I was a footballer."
Next up for Leicester is a trip to Arsenal but Ranieri says his team will continue to play the same way as they have done all season against the Gunners."[The Man City win means] Nothing, I'm sorry," he said. "We know it is a crazy league and then we have to try in this crazy league.
"There are some big teams who have to win. We now will enjoy, of course. We don't leave anything but we want to fight – without pressure.
"For us it is important to play and continue in this way because it is a strange league."