Spurs began the season in sublime form, going 10 matches unbeaten to top the league, but five defeats coupled with injuries have seen them fall to fifth at the halfway stage of the season -- six points behind leaders Liverpool.
James Maddison, Cristian Romero, Rodrigo Bentancur, Micky van de Ven, Ryan Sessegnon and Manor Solomon are out injured while Ivan Perisic is sidelined for the rest of the season with an ACL injury.
While most players are set to return to action in the next few weeks, Postecoglou does not expect reinforcements when the transfer window opens on Jan. 1. In addition, long-time keeper Hugo Lloris could also leave.
"The transfer window? Nothing magical is going to happen in the window. What we need to do is keep building," Postecoglou told reporters ahead of Sunday's home game against Bournemouth.
"We've had one window with this team to change to around and to things differently. The fact we're in the position we are is a credit to the players. Throughout all the challenges we've had, we keep ploughing forward.
"We'll see what we can do in January, but ultimately it's about building a side to get us where we want to get to."
Postecoglou's aggressive and fast attacking style of play has taken its toll and the Australian said sustaining that over a season requires a stronger squad.
"It has tested the limits of our ability to play the football we want in the context of the injuries we have," Postecoglou added.
"It would be unfair to judge some players. The way we play takes a hefty physical toll compared to how other clubs play. For us to sustain it, we need a strong squad and we're nowhere near that at the moment.
"We've had one window, so it was never going to happen. But we want to compete and we've got ourselves into the position where we can compete. That's what we need to keep pushing forward for."
