The Giallorossi travel to Camp Nou for Wednesday's opening leg as they look to reach the semi-finals of Europe's elite competition for the first time since 1984.
Tacchinardi told Omnisport: "Roma stand no chance. This season's Barcelona is possibly one of the best of the last 20 years. Even their bench is deep.
"Messi is reaching amazing levels again and even to stop only him is not easy. Roma would need two perfect games.
"Like it or not, you park the bus. If you attack them and leave them 50 metres, they will kill you."