The Partenopei booked their place in the final after beating Siena 3-2 on aggregate in the semi-finals, setting up a clash with the Bianconeri on May 20.
However, their league form has been poor of late with Walter Mazzarri's men currently lying in 6th place, six points behind third-placed Lazio who currently occupy the final Champions League qualification spot.
And considering the Coppa Italia will give Napoli the chance to land their first major piece of silverware since they won Serie A in 1990, Cannavaro admits his side have been distracted by that prospect lately.
"I cannot deny that the mind wanders the May 20, but we have to stop it," the 30-year-old told Radio Marte.
"I won't deny that the thought of being able to lift a trophy with Napoli is wonderful.
"It would be a dream come true, but now we must think about Serie A; we want to finish the season strongly."
Napoli were defeated by Atalanta 3-1 in Wednesday night - a result Cannavaro believes the Napoli faithful have every right to be upset about.
"On Wednesday I watched the game against Atalanta from the stands, and I must be honest in saying that I didn't see the usual determination from the team," the Italian centre-back admitted.
"The fans had the right to whistle at the end, as during the game I expected a greater effort.
"Our fans are a force behind us and hopefully their good feeling will return soon and we can overcome this difficult time."
Napoli have picked up just one point from their last four games, and have lost three straight matches to Juventus, Lazio and Atalanta.