The Frenchman was frustrated that his side failed to take their chances in Sunday's defeat to Napoli and is concerned over the injury suffered by Kevin Strootman
A late header from Jose Callejon saw the Partenopei seal maximum points and leave second-placed Roma 14 points adrift of leaders and reigning champions Juventus.
"We played with character and maturity, so I don't think the defeat was deserved. We saw tonight that in football the best team doesn't always win," Garcia told Sky Sport Italia.
"I am not worried, as you need a little bit of luck to score. Our shots went very close to the goal, whereas Napoli's chance hit the bar and went in. We shouldn't forget that [Pepe] Reina made some great saves.
"It's true we can be more effective in attack, but we hadn't played this well in a while and to do so on Napoli's home turf is really impressive.
"Maybe we have also lost some confidence and determination in attack, so we need to work on that. The goal is a good Napoli move, but it was simple to defend against.
"Mathematically the Scudetto race isn't over, but realistically it is. There's a huge gap now and we have to win our next home game, with hopefully some players returning from injury. Francesco Totti will hopefully be available.
"Of course I remain confident of second place. If we play like this, we will win many games for the rest of the season."
Roma lost midfielder Kevin Strootman to a knee injury early in the encounter and Garcia admits he is concerned the Netherlands international could have suffered some serious damage.
"The main concern is not the defeat, but Kevin Strootman," he added. "We hope that we haven't lost him for a while. He is in a lot of pain, the knee is swollen and he had a nasty knock, then sprained it a few minutes later."