The Socceroos boss was nonetheless impressed by his side's display in the 1-0 defeat to Croatia and is relishing facing Chile in their World Cup opener on Friday
The Socceroos lost their final warm-up game before the World Cup, conceding a Nikica Jelavic goal in the second half of the friendly, though they made life difficult for their European opponents throughout the encounter.
Postecoglou singled out the work of his defence, well marshalled by the fit-again Matthew Spiranovic, as a significant improvement from the underwhelming 1-1 draw with South Africa last month and has now called on his side to improve their potency in attack.
"Overall it was OK," he told Fox Sports.
"I thought our general play was quite good, particularly in the first half. Defensively we looked strong which was pleasing. Bit of an unfortunate goal. We probably just lacked a cutting edge up front.
"With better decisions we could have created some opportunities for ourselves. That's probably the one area we were a little bit disappointing.
"I thought Bresc [Mark Bresciano] helped that when he came on, he found little pockets and was causing some problems around the edge of the box.
"Everyone got through it, it was a tough game in tough conditions against a quality opponent."
Postecoglou's attention now turns to Australia's first game of the World Cup against Jorge Sampaoli's Chile on Friday.
"Every day is a challenge and we're looking forward to it," he said.
"The players have worked really hard, obviously now with that game out the way our next focus becomes the first game against Chile and it's going to be a fantastic test for us. One we're looking for to."
Captain Mile Jedinak made his return from an ankle injury and the Crystal Palace midfielder said he had pulled up well.
"I feel great," Jedinak said.
"I'm glad I got the 75 minutes under my belt. Now I just push forward, get myself right and be ready for that big one next Friday."