Spurs go to Nottingham Forest on Boxing Day on the back of Sunday night's 6-3 home thrashing by Liverpool.
Postecoglou said, "I still feel like the players, and I see, that they have still got real belief in what we are doing. It is difficult because it is a tough day for the supporters, the players and for all the people who work so hard at the club. From my perspective I take responsibility for that because I am the one that is charting this course for us. It’s all hopefully for a greater purpose.
"What I try and sort of reiterate is that it's all hopefully for a greater purpose. And, again, that's my ultimate responsibility is to try and bring success to the club. But you understand in the meantime, you know, it's not nice seeing the players out there doing everything in their power to try and get a result. But obviously with the situation we're in there are limits to what they can do. So you feel, I certainly feel that responsibility. But as disappointed as they are, they're still very, very determined to continue.
"I don't think there's any doubt we can challenge most of the teams in the league. I think we've shown that already. Look, I said after the game, Liverpool were too good for us. They're a very good team. They're in great form. They're in a great moment in terms of where they're at right now.
"They're in a sort of sweet spot of great form, very settled, all their players healthy. So they're probably in the best position they've been and fair to say we're not. And a combination of that and we were just, we weren't anywhere near the level we needed to be to try and compete with the best team in the league. So you accept that. It doesn't feel nice, but you accept where you're at. And the goal is to bridge that gap."