William Gallas was stood in an offside position as Tom Huddlestone’s shot sailed past him and into the net, leading to the flag being raised.
However, referee Mike Dean, after consulting with his assistant, proceeded to give the goal and Spurs all three points.
Greening insists that decision was farcical, with even the Spurs players unable to believe their luck.
"For one he was in an offside position and interfering with play. The linesman gave offside and I don't know why the ref tried to get involved really.
"Aaron Lennon admitted it was definitely offside, so I don't know what the referee saw."
He added: "It was an even game. We got a good goal and then were a bit sloppy to let them back into it straight away.
"They've come out strong in the second half, but at the end of the day, the referee's decision has killed us."