Gonzalo Higuain missed a glorious first-half chance to put Argentina 1-0 ahead, while Lionel Messi also squandered a good opening early in the second half yesterday.
Instead Germany, who controlled possession, struck an extra-time winner through Mario Goetze.
"It was a very balanced game," Sabella said. "They had more possession, but we had more cutting edge, more chances.
"When there are chances in a game that is so evenly balanced, you have to take them. We lacked a bit of efficiency."
Sabella, meanwhile, praised his players for recovering from a gruelling semi-final against the Netherlands to take Germany all the way to the wire.
"We played a day later and extra time, and the only thing I can do is congratulate my players," he said.
"The work they did was extraordinary and we also congratulate Germany."
Argentina were bidding to claim a first title since 1986, but although they fell short, Sabella said they had done everything in their power to win.
"It is very bitter," he said. "We had a great team to get to the final and obviously we wanted to win. To be perfect, we needed to be more efficient.
"I am sad for the players, for the normal pain of losing, but also satisfied, because we have an extraordinary group that gave everything.
"They were warriors, at least in the football sense. I congratulate them, obviously, because there is nothing else to do.
"A coach always has to judge the performance, which I think was very good, and above all the effort. They gave every last bead of sweat for Argentina."
Sabella added: "Bearing in mind the opponent and the circumstance of playing a day later, it was our best game.
"After 24 years, the players made history. They didn't win the gold, but they won the silver. We go away with a bittersweet taste.
"It is a double sensation. One of sadness, because when you get to a final, you want to win, but also of satisfaction, because the players gave everything. You can't criticise them for anything."