Referee Rob Styles pointed to the spot after a 50-50 tussle between Anthony Gardner and Robbie Savage in the 35th minute as City squeezed home 1-0 in Saturday's Premiership opener.
The Spurs players looked perplexed at the decision but that mattered little as David Dunn slotted home from 12 yards despite the best efforts of Kasey Keller.
"It was never a penalty," said a disappointed Glenn afterwards. "Savage has fouled our player. He's all over Tony (Gardner). I've watched it again and I can't see a penalty.
"It's a poor, poor decision and the difference between us getting something out of the game and getting absolutely nil. That's hard to take."
We went on to dominate the second half and came within inches of equalising when Robbie Keane hit the inside of the post.
"If we'd have got to half-time at 0-0 I think we would have won that game. It was a poor decision and sticks in the throat."
Glenn Hoddle described Birmingham City's penalty as a 'poor, poor decision' and left St Andrew's convinced we would have won had it not been awarded.