The northern province suffered a harsh lesson at Allianz Park on Saturday with the English Premiership side running out 33-17 victors.
Though disappointed with his side’s performance Kiss expressed huge admiration for the way the winners went about their business.
“We’re extremely disappointed, to tell you the truth. They teach us a lesson each time we play them.
"There is a ruthless efficiency about them,” Kiss said.
“At the beginning of the season I said the one team that will challenge Toulon will be Saracens. Each week my belief in that statement becomes stronger.
“The second half was disappointing.
"I thought in the first half we did enough to be better than where we were but when you get down that end of the pitch, you back yourself to go to the sideline and you don’t quite know what you need to do at the setpiece to set it up then it’s costly against a team like Saracens.
“We only have ourselves to blame. It’s a hurting dressing room.
"It was an opportunity lost in a lot of ways because of what we did early in that first half but we just didn’t get back to that part of our game that we knew we could play to.”
Owen Farrell was named man of the match in front of England head coach Eddie Jones, despite an off day from the kicking tee that saw him miss four of his nine shots at goal.
Farrell’s vision and athleticism were the source of the 53rd-minute try scored by Duncan Taylor that swept the match beyond Ulster’s reach and the 24-year-old is expected to start the RBS 6 Nations opener against Scotland at inside centre.
“I thought Owen was brilliant, he was outstanding. When he missed kicks... he just puts it behind him and then gets the next one over,” Saracens’ coach Mark McCall said.
“He usually gets the really important ones over. He had a great game. The speculation seems to be that he will play 12 for England at Murrayfield.
"Clearly, he has the skill set to do it if you want that kind of 12 there. He’s a brilliant rugby player.”
Billy Vunipola, Taylor, Maro Itoje and Schalk Brits helped themselves to tries as Saracens secured a home quarter-final despite having one game left to play, in Toulouse on Saturday.
Tries: B. Vunipola, D. Taylor, Itoje, Brits. Cons: Farrell 2. Pens: Farrell 3.
Tries: L. Marshall, Humphreys. Cons: Jackson, Humphreys. Pens: Jackson.
Ransom, Ashton, Bosch, Barritt, Wyles, Farrell, Wigglesworth, M. Vunipola, George, du Plessis, Itoje, Kruis, Rhodes, Fraser, B. Vunipola.
Hodgson for Ransom (61), de Kock for Wigglesworth (63), Barrington for M. Vunipola (65), Brits for George (56), Figallo for du Plessis (56), Wray for Fraser (63).
J. Hamilton, D. Taylor.
Payne, Trimble, L. Marshall, McCloskey, Gilroy, Jackson, Pienaar, McCall, R. Best, Herbst, O’Connor, van der Merwe, Diack, Reidy, Wilson.
Scholes for L. Marshall (71), Humphreys for Jackson (61), P. Marshall for Pienaar (75), Black for McCall (74), Herring for R. Best (61), Stevenson for O’Connor (74), C. Ross for van der Merwe (66).
Lutton. Sin Bin: Gilroy (61).
Jerome Garces (France).