Rooney apologised on Wednesday after images emerged of him on international duty looking worse for wear having dropped in on a wedding party over the weekend following Friday's victory over Scotland at Wembley.
The incident seemingly angered the Football Association who announced they would be reviewing what players are allowed to do in their free time, while Sky Sports reported United manager Jose Mourinho was furious that the forward had been with members of England's backroom staff into the early hours of Sunday.
“I feel sorry for the players," Klopp told reporters on Thursday.
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"We live on the sunny side of life and all this stuff but in the end, maybe it is a surprise, there is a human being behind the kid.
“This generation is the most professional generation of footballers - not only in England - we have ever had. All the legends you admire drank like devils and smoked like crazy and were still good players. Nobody does that anymore. I’ve no idea where Wayne was but I’m pretty sure it was not that serious.”
The Liverpool boss is preparing his Premier League leaders for Saturday's trip to Southampton, but will have to play a waiting game over the fitness of Adam Lallana.
Lallana's form this season has been superb with the midfielder having at last found his feet at the club after a mixed start at Anfield following a 25 million-pound ($31.19 million) move from Southampton in 2014.
He continued his good start to the season on the international stage with goals in England's games against Scotland and Spain, before suffering a groin injury against the latter at Wembley on Tuesday.
“With Adam we don’t know yet exactly," Klopp said.
“Of course, nobody comes off the pitch when they don’t feel anything and I’ve spoken to him already, he felt (something) but we couldn’t do a scan until now, so we have to wait for this.
"As you can imagine, it will be close. The time until Southampton is short, so I don’t know. Hopefully, it is not too serious, but we have to wait.”
(Reporting by Toby Davis; editing by Ed Osmond)
