"I thought we were super. It was a great performance and it came down to a lottery in the end," added Redknapp.
"They couldn't beat us in 90 minutes plus extra time, we didn't deserve to lose and I thought we were fantastic."
Jamie O'Hara and David Bentley failed to convert from 12 yards while United's four takers all found the net.
Redknapp admitted after the match that he had suspected the shoot-out might prove too much pressure for some of his young charges.
"I have to be honest, we were not that confident with our penalty-takers really and you looked over there and they had very confident penalty-takers," he said.
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