Dwight Gayle fired Peterborough ahead in the 15th minute but they remain in the Championship bottom three after Sam Byram levelled for Leeds in the 57th minute.
Gayle almost won his side a penalty in the 86th minute when he was fouled by Paul Green on the edge of the area and Ferguson was left to curse spurned chances.
"It's not a good point," he said. "It's really disappointing that we dropped two points.
"It was a great opportunity to get three points and out of the last three draws I would say tonight was the biggest opportunity.
"But unfortunately we only take a point. We had seven or eight chances to get the second goal and we've not taken them."
Ferguson will be meeting with referees' boss David Allison over a series of decisions during the season and was angered when Stephen Warnock escaped a red card for bringing down Kane Ferdinand on the edge of the box.
"I've just seen the referee and to be fair he said he'd watch it again," said Ferguson.
"You've got to be denying a goalscoring opportunity and if that's not a goalscoring opportunity I don't know what is.
"But to be fair to the ref he said he'd phone me and apologise.
"That might stop us going down and it might not stop us staying up, but at least he's done that.
"If it happened at the other end the referee would not have got out of here alive if he hadn't given a red card."