Jesus Ramirez scored the only goal of the game seven minutes before halftime when he pounced inside the six-yard box to convert Ender Echenique's low cross from the right and condemn Popovic's side to a second consecutive defeat.
"There's a lot we have to assess, but in the end, we're disappointed we lost the game," said Popovic, whose side lost 2-1 in their previous outing against the United States in October.
"We were probably a little bit too open. Venezuela, technically, were very good and were able to get into our box, and obviously scored a goal, but it was a little bit too easy on our part.
"We know we have to be better, but that's part of what we're doing here and part of the process."
Preparing for the Australians' sixth consecutive appearance at the World Cup, Popovic fielded an experimental side as he continues to assess his squad ahead of the finals in the US, Canada and Mexico.
The head coach gave international debuts to four players, including Melbourne City goalkeeper Patrick Beach, and the 22-year-old intervened on several occasions to keep Australia in contention.
"It's disappointing not to get the result, the win," said Beach. "That's what we try to do in every game.
"I thought we played very well in certain patches. Venezuela had the ball a lot of the time and we dug in deep and defended really well but unfortunately we couldn't get the result.
"Pretty busy in the first half and had a save early in the second half. I was really happy that I was able to make those saves for the team and help them out when I was called upon."
