The Rome club were beaten 2-1 as Rossi was forced to do without Cristian Ledesma, Stefano Mauri, Emilson Cribari, Sebastiano Siviglia and Mobido Diakhite.
"We have some young players with quality and it is right to give them the chance to play. What I would prefer is the opportunity to make my choices more carefully rather than having them forced upon me," said Rossi.
"As a man of sport, when you lose then something has inevitably gone wrong. Talking about absentees is unfair to those who played the 90 minutes.
"It is true we are dealing with a remarkable series of long-term injuries, but we have earned our place in the Champions League and will try to make the most of it."
He added: "This team may not be perfect, but it has extraordinary courage. A few incidents did not go our way, such as a few offside decisions, and in tricky matches like this those moments can make the difference."