Verbeek said the game offered some positives for his team but was concerned the Socceroos gave the ball away too much.
"The organisation was not good, the first goal was a present ... I think we need to keep the ball better as a team," he told reporters after the match.
It was still a training session, Verbeek added however, and was not cause for concern ahead of the first Group D match against Germany on June 13.
U.S. coach Bob Bradley said the friendly was a "good tune-up" but added his main concern had been to get through the game without any major injuries.
American captain Carlos Bocanegra, struggling with a hernia, played for 55 minutes but Australia's injury concern Harry Kewell (groin) remained a spectator throughout.
Striker Edson Buddle opened the scoring in the fourth minute with a well placed drive past Australian Mark Schwarzer's outstretched left arm and the U.S. looked the stronger team for most of the first half.
Tim Cahill levelled the scores on 19 minutes against the run of play, and Schwarzer kept matters even with a good save from Fulham team mate Clint Dempsey after a slick passing move by the U.S. from inside their own half.
But he could not stop Buddle's headed second just after the half-hour and substitute Herculez Gomez sealed the victory in time added on.
Australia, who arrived first in South Africa for the June 11-July 11 tournament to better acclimatise to Johannesburg's high altitude climate, created few chances to start with but looked more dangerous in the second half.
The U.S. play England in their World Cup opener on June 12 and then face Slovenia and Algeria.
Australia play Ghana on June 19 and Serbia on June 23.
