A hat-trick from Tom Eaves condemned Crawley to a 3-0 defeat at Shrewsbury and left them 11 points adrift of the top six with just half a dozen games to go.
"It's going to be extremely tough," said Barker. "But I'm determined that the season isn't going to fizzle out and I'm going to make sure that the players think that as well.
"We want to finish as high in the table as we can.
"I can't argue with the work ethic or the way they've put in place what we were trying to do. I can't argue with any of that but all that was missing was the first goal."
Barker insisted he was encouraged by much of what he saw from his side but admitted the finishing of Eaves was the difference between the teams.
"I said to the players afterwards that I don't know whether to feel a little bit embarrassed or actually feel sorry for them because I thought, and I'm sure Graham doesn't agree, that we were by far the better team
"We had the most possession, most chances, most shots, and got beat 3-0.
"Eaves was excellent. He was a real thorn in the side and it's a steep learning curve for our young strikers, particularly people like Jamie Proctor, but he was the difference."