Callum Morton’s first half double cancelled out Ronan Darcy’s early opener as the Reds fell to their fourth League Two defeat in five games.
Kelly, who was captaining Crawley in the absence of Ben Gladwin, said: “I think we started the game really well, for the first 25 minutes. We scored early, which is what we wanted, and dominated the game.
“We could have been three or four up – but we’ve said that a lot this season.
“There’s a number of things we need to work on, and being more ruthless in the final third is one of them.”
Crawley manager Scott Lindsey said the Reds ‘gifted’ Rovers their goals at The New Lawn – a sentiment that was echoed by his captain.
Kelly said: “The boys knows that we’ve made two really bad mistakes. But, again, it would help if we were two or 3-0 up.
“It takes all the energy away from the game, but we’ve only got ourselves to blame. Everyone’s just got to do better.”
Morton struck what proved to be Forest Green’s winner deep into second half stoppage time.
Kelly revealed Rovers’ second knocked the stuffing out of the Reds, but the midfielder admitted Crawley’s attacking players did not do enough to test Forest Green keeper James Belshaw in the second half.
He continued: “Going in at 1-1 [at half-time] would probably have been harsh on us, so to go in 2-1 down sort of deflated us. But, again, we have to do better. We have to come out in the second half and be better as well.
“I don’t think we worked their goalie enough in the second half. We spoke about that – getting balls in the box and taking shots and just being better in the final third as a team. As a front five I think we can all do better.”
Next Saturday sees Crawley turn their attentions to cup matters. The Reds travel to League Two rivals Notts County in the first round proper of the FA Cup.
Looking ahead to next weekend’s game at Meadow Lane, Kelly said: “As players we just want to play games. It’s a game that we want to win.
“The FA Cup is a special competition for everyone, so we’ll go in next week and look forward to Notts County away.
“It’s a great stadium to play at, but it’s another game we want to try and win.”