Allowing Andrej Kramaric to go out on loan to German club Hoffenheim has left Ranieri with just three strikers and the Italian would like to lessen the burden on main man Jamie Vardy.
Leicester's leading marksman has netted 15 Barclays Premier League goals this season but he has gone six league games without scoring.
"We have our eyes open," said Ranieri. "If there is a good opportunity for us, we are ready. Now I want another attacking player - a striker.
"I am very confident. My staff is fabulous, every day they are working, because when I ask about something they are ready.
"I'd like to do my business as soon as possible."
Asked about the type of striker he would like to bring to the club, Ranieri said: "Andrej wasn't the main striker, he was more behind Vardy.
"But behind Vardy I prefer Leonardo Ulloa and Shinji Okazaki, because Ulloa covers the ball very well, he's a fighter, and Okazaki is another who presses everybody every second.
"Kramaric has fantastic skill but sometimes he rests and recovers. This team can't recover, they need to run, run, run.
"When I say we are building a good team, I would like to have two players for each position, so when I change, you don't see the difference.
"Kramaric didn't play, I have Ulloa, Okazaki and Vardy so I need one more I can change so the result is the same, I will have good strikers on the pitch."
Ranieri believes letting Kramaric spend the rest of the season at Hoffenheim will be good for all parties.
The 24-year-old has joined the Bundesliga side after failing to break into the Leicester team since Ranieri's arrival in the summer.
"I think in this moment he needs to reinvigorate his mind because in my mind he is a very good player," said the City boss.
"He has very good skills and qualities, but this season is difficult for him to play with me.
"He can't lose this season because it is very important for him, and for us. It is important he goes to the European Championships. It is better for the team, the club and for the player for him to go and play."