"We're not happy with that performance," Kiffin said in his weekly Q&A.
But Kiffin also stressed that one loss was not the end of the season for the Trojans, who still have nine games left on their schedule to prove their worth.
"We have to make sure they understand the world's not over; it's one game. What we've got to do is learn from that and we've got to improve," Kiffin said. "There's millions of stories of teams losing early and having great seasons, and I expect us to do that."
The first game on the rest of the Trojans' schedule is back in Los Angeles, hosting the Cal Bears on Saturday afternoon. USC has beaten Cal eight straight times, including wins of 48-14 and 30-9 under Kiffin.
USC will have to deal with Bears junior wide receiver Keenan Allen, a multipurpose threat with 379 combined yards in three games. Allen has scored a touchdown via the air, on the ground, and on a punt return this season.
"He's hard to deal with," Kiffin said of Allen. He's big, he's physical, he's fast. He returns punts, too. He is one of the best in the country.
Allen caught 13 balls for 160 yards last season against the Trojans, but they were able to keep him out of the end zone. Doing so again on Saturday will go a long way in helping USC get back on track.