"I don't know how I missed and I still can't believe it," Vucinic told the Corriere dello Sport.
"It was a really awful penalty. If I had shot left or right it would have gone in because the goalkeeper didn't move.
"The fans were amazing yesterday and I'm just upset that we couldn't finish the job and knock Arsenal out.
"I have to be honest, I don't know what the Coach said when we got back in the dressing room, I was too upset.
"We know we have failed in the Champions League and now we have to do whatever we can to repay our fans.
"I hope I can play against Sampdoria. I was in pain yesterday but I played through it due to the incredible atmosphere."