A penalty from Jaime Mata was the difference between the two sides at the Coliseum Alfonso Perez, as Barca lost away to Getafe for the first time in La Liga since 2011.
Busquets admitted his team struggled to hurt the hosts and said they must do better in future.
“We knew it would be hard. Once they got in front they were very comfortable. We tried but it wasn’t our day,” he said.
“We tried to give a certain fluidity to our football. We tried to pass the ball quickly but it was difficult once they went in front. We weren’t sharp enough tonight. We kept trying, we had chances at the end but we have to accept the result.
“I think in the first half we did find space in wide areas but once they went in front they are good at closing the space down. We have to keep improving, the season has only just started. We need to just get back to winning ways as soon as possible.”
Barca will have to bounce back quickly with games now coming thick and fast. Next up is a visit from Ferencvaros in the Champions League on Tuesday.