Jones told reporters: "I suppose it was a bit of nerves. When we were 15-9 up, we needed a penalty just to take it away from them but we didn't get it.
"The Aussies will always fight right to the end, we learned that here last year with Wales. But we are still confident we can win the series.
"We have a few days to take in what's happened and then a few more days to realise that this is the biggest game we can possibly play in barring a World Cup final. If we can't get up for that we're struggling."
The two sides will meet in the final Test match on Saturday.