The Reds could not build on their midweek victory over RB Leipzig in the Champions League Round of 16 to lose against Everton at home for the first time in 22 years.
Goals from Richarlison and Gylfi Sigurdsson in each half helped Carlo Ancelotti’s men to secure a first win in the league since a 2-1 win over Leeds United on February 3.
Klopp’s men have lost four consecutive time at Anfield and their hope of defending their Premier League game has taken another hit as they are now 16 points behind runaway leaders Manchester City, who will be playing Arsenal on Sunday.
"It is (tough to take) but we conceded this early goal which was completely unnecessary and we had to defend better,” Klopp told reporters after the game.
“We had to chase the game and did it well creative wise, we created some in the first half and even more in the second half but we did not finish our situations off.
"We made one mistake in the first half and they used it. I don't like to talk today about the good stuff because we lose the game and we feel that deeply, I have to use it tomorrow and it is our lifeline to keep going. We have to improve on the finishing stuff and then we will win football games.
"Decisive margins, to score a goal you have to create a situation and finish it off. There is no alternative but to keep going. You concede which is not cool, lose Jordan Henderson which is not cool and I feel the boys dealt with it quite well, could they deal with it better? Maybe. We will keep going."