The second-time presidential hopeful was the target of "what appears to be an attempted assassination" at his golf club in Florida on Sunday, the FBI has confirmed.
It comes two months after Mr Trump was injured in an assassination attempt in Pennsylvania on July 13.
Federal Housing Minister Clare O'Neil said the latest incident was "absolutely awful" and reflected on the ramifications for Australian politics.
"It worries me because America is such an important and powerful democracy, and it does affect us here in Australia," she told the ABC on Monday.
"We're very lucky here and I never want Australians to lose sight of that."
Australia's strict gun laws and a political culture where differences are resolved at the ballot box rather than by violence were key factors.
"This is not the case in many countries in the world, and it's something precious and it's something we've got to value," Ms O'Neil said.
"It's a little bit fragile at times and we need to support it and protect it."
Foreign Minister Penny Wong said she was relieved Mr Trump wasn't injured.
Penny Wong says there's no place for political violence. (Joel Carrett/AAP PHOTOS)
"Political violence has no place in any society - certainly has no place in a democracy," she told ABC radio.
"This is another dreadful demonstration of potential political violence."
According to the Reuters news agency, Mr Trump was targetted while golfing on his course in West Palm Beach.
US Secret Service agents spotted and fired on a gunman on Sunday in some bushes near the property line with an AK-47-style assault rifle.
He was roughly 400 metres away from the presidential candidate.
The man was later taken into custody and Mr Trump was confirmed to be safe and well.
In July, Trump was grazed in the right ear and one rallygoer was killed in the gunfire.Â
The gunman, identified as a 20-year-old Thomas Crooks, was shot and killed by a Secret Service sniper.
with AP
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