The former Arsenal midfielder has voiced his dismay with the Catalans' performance in midweek and is determined to bounce back against Athletic Bilbao
The Catalans had to make do without the likes of Victor Valdes, Dani Alves, Jordi Alba, Adriano, Lionel Messi and Alexis Sanchez in the Dutch capital.
However. Fabregas feels they should still have done better and has demanded a reaction against Athletic Bilbao on Sunday.
"We're a bit short of players, but that's no excuse," the midfielder said at a press conference.
"We have always been self-critical. That was our first defeat in 21 games, and now we have work out what we got wrong and where we need to make improvements.
"We have to demonstrate our ability to win matches and our mental capacity to react to defeats. We are a competitive team and we know that these things can happen, but what happens next depends entirely on us.
"We will bounce back against Athletic Bilbao."
Barcelona currently sit atop of La Liga with 40 points from 13 games, while Athletic sit fifth in the table.