The Reds were comprehensively beaten in front of a Premier League record crowd at Wembley , slipping 2-0 behind after just 12 minutes to goals from Harry Kane and Son Heung-Min .
Son's strike came after Lovren completely mistimed a header, allowing Kane to tee up the South Korean, and while Mohamed Salah's strike briefly cut the deficit further goals from Dele Alli and Kane put the result beyond question.
Lovren watched those last two strikes from the bench after being subbed after just 30 minutes, and his manager admitted the defender's performance was not up to scratch.
"The first goal was a little throw in and we are not really there. It was just really bad, bad, bad defending," Klopp told Sky Sports after the final whistle.
"The second, a counter attack, when the ball passes Dejan Lovren it is already too late.
"If I am involved in this situation on the pitch, then Harry [Kane] cannot get the ball."
Klopp, however, underlined that despite Lovren's mistakes, it was the team as a whole that failed at Wembley.
"Now we have to realise that we are responsible for this and nobody else. Of course we can fix it and we have to fix it as well," he added.
"The whole game the whole result was all our fault - Tottenham was good, they needed to be good, but we made it much too easy for them."