The Partenopei fell three points behind third-place Lazio thanks to today's 2-2 draw at the San Paolo.
"We lacked the desire to win," snapped the striker after the final whistle.
"In football that is crucial, otherwise we're going nowhere like this. Now we have to look forward, but there is bitterness considering we were 2-0 up.
"As for third place, we have to keep on fighting, as we want to get back into the Champions League."