Barcelona were only 1-0 up when the young Frenchman found the woodwork, but the hosts increased their lead just moments later.
They went on to collect a 4-0 win, enough to overturn the 2-0 first leg deficit.
“Barcelona are a great team, but they are human,” he added. “I’m disappointed with how the game went.
“We were very happy with our display at San Siro and to come here with an advantage. We battled, but this is football.”