The home side ran in five tries to France's one to secure a 39-13 victory, Guilhem Guirado crossing for Les Bleus.
France, who finished fourth in this year's RBS 6 Nations and last won the tournament in 2010, have now lost 13 of their last 19 matches and Saint-Andre admitted his side had been thoroughly outplayed.
"They won all the contact areas," he said.
"They go forwards all the time. They put a big tempo in the game. We missed so many tackles and we were all the time in difficulty.
"Fair play to Australia. They played very well, they did very well and scored five tries to one. We were struggling to keep the ball more than three phases.
"There was more activity, more urgency, more skills in the Australian team than in our team. Congratulations to them.
"It's the end of a long, long season for our players. There will be another game in November in Paris and they will see one French team completely different."
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