Defender Portanova was charged for failing to report an incident of match-fixing two years ago in a Serie A match between Bologna and Bari.
“I have lived with so much anger for the last four months," he said.
"That's what happens when you know you're innocent.
“I believe there were no grounds to denounce me and I hope that such incidents do not happen again.
“I want to thank all those who were close to me in recent months, and it is for them that I will put all my efforts from now on.”