The Bantams were beaten by the Cumbrians thanks to goals from two of their ex-players in Jordan Gibson and Omari Patrick.
Bradford failed to muster a shot on target and left the pitch to angry chants from the 1,200 strong travelling fans.
“When you don’t have a shot on target you’re going to get that,” admitted Adams.
“If you haven’t seen your team play to the best of their ability then you’re going to have that reaction from the supporters.
“We made changes and the players that came on and who were on the pitch didn’t do well enough.”
Bradford did manage to enjoy the better of the early exchanges but lost top-scorer Andy Cook with a dead leg after half an hour.
A Yann Songo’o header was then ruled out for a foul on goalkeeper Mark Howard but Bradford could not seriously trouble the hosts again.
Adams added: “We started the game very well on the front foot and created some good openings.
“Yann Songo’o had one disallowed that looks like it was a goal and Oscar Threlkeld had a great chance before that.
“Eventually they scored right on half-time and that sets us back. Second half we haven’t created any real opportunities.
“We haven’t hit the target in the game and that is hugely disappointing.”
Carlisle United: Howard; Mellor, Armer, McDonald, Guy; Dickenson, Mellish, Feeney, Whelan; Gibson, Omotoye (Patrick 75). Unused substitutes: Norman, Devine, Riley, Abrahams, Fishburn, Senior.
Bradford City: Hornby; Threlkeld (Foulds 60), Ridehalgh, O’Connor, Songo’o; Cooke (Robinson 76), Cook (Vernam 29), Gilliead, Kelleher; Watt, Angol. Unused substitutes: O’Donnell, Sutton, Cousin-Dawson, Lavery.
Referee: A Haines (Tyne and Wear).