Fabio Quagliarella scored the winner from the spot in the second half.
Ranieri said, “I am happy for the mentality we showed and the determination we had to snatch the three points. Once again, we saw a group that is working well.
“I had said we had conceded too many goals this season, and I didn't want to concede more. I am really happy about the commitment of the lads, I am satisfied with this group."
The veteran coach is off contract next month.
He added: “There is no news, we'll see what happens next week. I am always optimistic, I always see the glass half full."