The Scottish champions have lost all of their four group games and are fighting now to at least finish third in order to qualify for the Europa League.
Celtic have taken the game to the teams in their group but have been left to rue the missed chances and their inability to not concede goals.
There are suggestions that Celtic, like Rangers, do not belong at Champions League level given the results they have managed in the group stage.
But Postecoglou stressed that Celtic’s performances do not suggest that they do not belong to that level and believes anyone saying that has some sort of agenda or has a biased point of view.
He insisted that the only thing his side need to improve to thrive in the Champions League is to learn how to take their chances.
Postecoglou said in a press conference: “We are not the only country that struggle to get results in the Champions League.
“I can only talk for my club but if anyone can tell me that in the four games we have played that we don’t deserve to be there or we’ve been outplayed or looked out of place, then I reckon they’re talking from an agenda or some sort of bias.
“The only question I have had after each of our games is the opportunities we missed and it suggests to me that we are going to improve in certain areas hundred per cent.
“It doesn’t suggest to me that we don’t belong in the competition that we haven’t earned the right to be.”
Celtic will be in league action on Sunday when they will host Hibernian at Parkhead.
