The 50-year-old was sacked as manager of the league's bottom club in October, but following Gigi De Canio's dismissal earlier this week, he has been reinstated.
The Rossazzurri have lost seven of their past 10 league fixtures, but Maran believes that they are capable of beating Vincenzo Montella's in-form side.
"I am pleased to hear the fans called for my return and that is an honour," he told reporters.
"It might seem like a cliché, but it isn't: I expect great support from the crowd in every home game. From the start I thought my sacking was unfair, but I wiped the slate clean. I am ready to begin again and fully believe we can achieve safety.
"Vincenzo Montella is a talented Coach in charge of a strong team, but I believe in my men against Fiorentina. This is the classic game we need to fire up the group and we can cause a shock."
Catania have won just three games in the league all season and are the only club in Serie A not to have picked up a point away from home.