Under new boss Mauricio Pochettino, Spurs made a strong start to the 2014-15 campaign, winning their first four matches, including both legs of their play-off against AEL to reach the group stage of this competition.
Since then, however, Tottenham have faltered, with only one win in their last six matches - a 3-1 triumph over Nottingham Forest in the League Cup third round last Wednesday.
That was followed up by a 1-1 draw at north London rivals Arsenal in the Premier League on Saturday, but captain Kaboul believes the standard of their display at the Emirates Stadium is something to which they should be aspiring to.
"The most important thing for myself, the players and the staff is that we showed a strength of mentality, we were strong on the pitch," the Frenchman said.
"We move on. This game is done, now we need to focus on Besiktas on Thursday.
"If we play the same way we did at Arsenal, we should have no problems, but we need to repeat that performance. We have set the tone."
In the opening round of Group C fixtures, Spurs held Partizan to a 0-0 draw in Belgrade, while Besiktas were denied all three points when Asteras Tripolis equalised late on in Turkey to clinch a 1-1 draw.
Their Turkish Super Lig encounter with Eskisehirspor on Saturday finished with the same scoreline, and manager Slaven Bilic was less than impressed with his side's showing.
"Honestly, our performance didn't deserve a win as we failed to create sufficient chances, especially in the second half," he said.
"Now, we must focus on our Europa League match against Tottenham. It is not going to be any easier than this one."
These two sides have only one previous meeting, in the 2006-07 UEFA Cup group stage, when goals from Hossam Ghaly and Dimitar Berbatov saw Spurs to a 2-0 victory in Istanbul.
Tottenham remain without Kyle Walker, who had surgery on an abdominal problem earlier this month, while Danny Rose was withdrawn late on at Arsenal and remains a doubt.
Beskitas, meanwhile, have doubts over Mustafa Pektemek, who took a knock against Tripolis and has not featured since.