Juan Bernat and Neymar, whose 31st goal in the competition saw him leapfrog Kaka as the top-scoring Brazilian, put the hosts ahead before James Milner's penalty on the stroke of half-time offered hope.
However, the Serbian side's late goal has changed the complexion of Liverpool's final game.
"Decision-making is the word for tonight, of course, because we couldn't find it", said Robertson.
"It isn't going to be easy, they [Napoli] are a very good team".
Klopp also felt one of the game's most influential players, Marco Verratti, deserved a red card for a challenge on Gomez.
Asked what more the officials could have done, Klopp replied: "I could say 500,00 things".
"We had six, seven, eight yellow cards and were close to a red card".
Liverpool must defeat Napoli in their final Group C outing at Anfield on December 11 to stand any chance of reaching the last 16 and Carragher is confident they can do it.
Such a regression in Europe would be a big blow to Liverpool, even if it could conceivably help Klopp's side in their fight with Manchester City for the Premier League title.
Jailed UK student's wife 'fears for his safety'
Mr Hedges was offered, and accepted, the services of a court-appointed lawyer and was also provided with translators, he said. He said he had held a contructive conversation on Thursday with his UAE counterpart Sheikh Abdullah Bin Zayed.
Liverpool need a win against Napoli to stand any chance of going through.
Klopp singled out Neymar for criticism after the match and said Liverpool were made to "look like butchers".
"Everyone was ready to suffer for each other. We'll be looking to do that, we know how big the game is and hopefully we can step up to the occasion".
PSG players celebrate the win over Liverpool. However, Klopp's side were completely overrun in the opening stages at the Parc des Princes.
Neymar was the chief culprit in the Parc des Princes as while the Brazil global produced some classy moments, including starting and ending the counter-attack which resulted in PSG taking a 2-0 lead, he dedicated far more time to throwing himself to the ground and rolling around.
He had been drawing fouls from opponents and whipping up a fervent home crowd before he burst down the left in the 37th minute, combining with Mbappe.
For all his rolling-around antics Neymar can turn it on in a flash and, having collected the ball 25 yards inside his own half, he shook off compatriot Roberto Firmino and exchanged passes with Mbappe before releasing his pacy team-mate down the left.
Di Maria brought down Sadio Mane just inside the area.