Fulham had twice taken the lead at Craven Cottage on Wednesday through a Kolo Toure own goal and Kieran Richardson's close-range strike, only to be pegged back by Daniel Sturridge's cool finish from an exquisite Steven Gerrard pass and Philippe Coutinho's 20-yard effort.
The hosts looked to be heading for a valuable point in their battle against relegation, but Riether scythed down Sturridge in the 90th minute, allowing Steven Gerrard to convert from 12 yards and keep Liverpool's Premier League title hopes alive.
Meulensteen felt his side deserved a point for the effort they showed, and was left to rue Riether's mistake.
"The third goal is a silly challenge from Sascha," he said. "He shouldn't have done it.
"The first thing he said when he came into the dressing room was 'sorry I shouldn't have done it'. We lost 3-2 which is hard to take, with the effort the boys put in they should have had a point I think."
Meulensteen felt his side paid the price for dropping too deep in their efforts to keep out a plethora of Liverpool attacks.
"The tactics worked well in the first half by stopping them getting into a rhythm and stopping Gerrard spraying those key passes," he continued.
"That's why we kept them at bay quite well in the first half. The second half they made changes, pushed people even further up the pitch which means we drop further back.
"In some ways we got away with it because we got 2-1 up, (but) there was a momentum where they really put us under pressure and I thought 'if we get out of this we'll be fine'.
"But Coutinho scored to make it 2-2, they pressed for another one and they got it."
