The 35-year-old attacker got a big chance to double his side's lead shortly after the break, but failed to beat Christian Abbiati with his attempt.
"My first thought was to go for the chip. I also considered dribbling a few more yards or shooting with power," Totti explained to Il Messaggero.
"The problem is quite simple to explain though. I was feeling a pain in my thigh and simply couldn't hit it hard. That's why I chose the simple solution. I was afraid that I would pull a muscle or something and face a lengthy spell on the sidelines."
Totti left the pitch to make way for Bojan Krkic 10 minutes after squandering his chance as the knock prevented him from playing further.