Ulster were knocked out of the quarter-finals of the Heineken Cup by Premiership leaders Saracens at Twickenham on Saturday, suffering a 27-16 defeat.
But, with just three regular season RaboDirect PRO12 games remaining, starting with the visit of Newport Gwent Dragons on Friday, Best knows Ulster must make a swift recovery.
"The Heineken Cup is the pinnacle of club rugby in the northern hemisphere and we wanted to win it," he said.
"Credit to Saracens, we were beaten by the better side but we are disappointed. Now we need to dust ourselves down and go again.
"We were beaten by a very well-drilled outfit but it is still disappointing because we wanted to win the competition. Now we have to take a look at ourselves."
Ruan Pienaar traded two penalties with Owen Farrell before the first try of the game, for Saracens flanker Will Fraser, was converted by the latter with the hosts 16-6 ahead at half-time.
Farrell kicked two more penalties and England wing Chris Ashton pushed Saracens further clear before a late Ulster rally as Iain Henderson scored a try.
And Best added: "We knew Owen Farrell wasn't going to miss many kicks and that proved to be the case.
"In the first half we didn't look after the ball well enough. We coughed up a lot of unforced errors and you can't afford to do that at this level.
"We talked about coming and taking it up a level but we didn't do that."
63x46.png){kind=logo}