Robbie, who was no longer on the pitch allowing spot-kick duties to fall to Jermain, believes it was more a penalty saved than one missed.
"Taking penalties, as I know myself, is not easy," said the skipper. "The keeper pulled off a great save and you have to give him credit for that.
"It is one of those things, Jermain is a top class player and I've seen him score many penalties over the years and he will again, no problem," he added, before reflecting on the first half incident that saw him tripped by Green when he found himself through on goal.
"I don't understand why it wasn't given as it was a clear penalty. I had the intention of getting the ball but I was fouled.
"We're disappointed we didn't win the game because we certainly deserved to get the three points."
Robbie Keane's sympathies were with Jermain Defoe after the late spot-kick at West Ham, while the non-award of a penalty was also occupying his thoughts.Jermain was denied a dramatic late winner by the reactions of Robert Green, who stooped low to help to block the England striker's penalty, a result of him being felled in the area by home full-back Lucas Neill.