Wolves had a strong spot-kick appeal dismissed in the early stages of their first away defeat of the campaign as they were knocked off the top of the table.
Madley, taking charge of his first match since awarding Stoke a controversial late penalty in a recent Barclays Premier League match at Swansea, refused to point to the spot despite Posh defender Mark Little appearing to handle Bakary Sako's cross.
It proved to be a pivotal moment in a match settled by a single goal - a free-kick from Posh skipper Michael Bostwick with 11 minutes remaining.
Jackett said: "It was a definite penalty early in the game.
"I would think it was as clear a decision as you will ever get and the referee had a good view of it.
"I can't comment on incidents in other games, but I'm left scratching my head as to how this one wasn't given.
"But that obviously wasn't the only reason we lost a game in which we were the dominant force.
"We had a lot of the ball around their box, but we didn't do enough with it. We weren't ruthless enough.
"Our attacking play disappointed me and that is something we will need to address.
"It is frustrating now that we go a fortnight without a game. We need to stay positive because we have a lot going for us."
Bostwick lashed a 25-yard strike past Wolves keeper Carl Ikeme as out-of-form Posh snapped a five-match losing streak in Sky Bet League One in style.
That was the hosts' only on-target effort of the afternoon, but Wolves had also created little in front of goal.
Wide man Sako fired one decent opportunity into the side-netting before testing Posh keeper Bobby Olejnik with a smart volley in the second period.
Leigh Griffiths and Danny Batth also squandered good headed opportunities as Jackett's men failed to find a breakthrough.