The 2006 World Cup winner made the remark after the Old Lady lost 1-0 at Parma on Sunday afternoon.
"We need great champions," said the striker. "Players of quality who can take Juventus back to the top.
"We could have caught up with Roma in the standings, but instead we missed out on a great opportunity.
"It was a poor game, but not because we were lacking in motivation. We wanted to do well, but we weren't able to.
"We wanted to reach fourth place in the table and now, instead, we probably won't be able to play in the Europa League either.
"We should improve and therefore will need important reinforcements to be able to do so."