"We should have had penalty just after half-time," he said, referring to Paul Robinson's challenge on Gabriel Agbonlahor.
"It's not been the best day for the linemen and the referee."
He was pleased with his side's performance, saying: "We've contributed here to a largely entertaining game.
"We have for the most part played terrifically.
"They dropped a little bit deep, which is understandable.
"Obviously Tottenham are going to throw everything at us.
"(It's) easier said than done to come out and still keep playing.
"Hopefully we can learn from that. We have a very young side here at the moment."
O'Neill is certain the result would not haunt his side, saying: "Absolutely not. These lads are game for anything. They feel they are capable of winning football matches home and away."