The Rossoneri had beaten Toro 2-0 in Serie A on Saturday and were unable to break them down after 120 minutes.
“I can't help but be satisfied with the performance, as it was the fourth game in nine days, yet we never lacked spirit or intensity," Pioli told Milan TV.
“It's a pity we didn't win it in the 90 minutes but we showed quality anyway, because it's not easy to convert five out of five penalties.
“We believe in our qualities. We always think positive during games and remain concentrated. That is what's paying off, because games are difficult and complicated, so you need that belief."