Speaking to Australia's Sky News in an interview on Thursday, Abbott also dismissed Democratic nominee Hillary Clinton's comments that half of Trump supporters were "deplorables."
"The vast majority of Trump supporters are not deplorables, they really aren't. They're decent people who want to see change inside their country and that's fair enough," he said.
But when asked about controversial comments made by Trump in a leaked video from 2005, Abbott said they were "gross".
"I think they're completely indefensible ... they were absolutely disgusting," he said.
'I admire America'
A fierce conservative and former Catholic seminarian, Abbott led Australia for almost two years from 2013 before he was toppled by current Prime Minister Malcolm Turnbull.
In the interview, Abbott was asked if he feared Trump's policy positions would be "discredited" if he lost.
"There will be tens if not hundreds of millions of Americans who will continue to support those positions," he said. "I'm proud of Australia, I admire America, I want to make America as great as it can be."
After the incident began to make news in Australia, Abbott wrote on his Twitter that some of Trump's views were "OTT" (over the top) but his positions on tax cuts and defense spending were "classic conservatism".
Abbott was unavailable when contacted by CNN for comment.
Abbott's time as leader controversial
Abbott's prime ministership was often marred by controversies and oddities, which saw his approval fall steadily until he was forced out in September 2015.
As leader of Australia's conservative Liberal National Coalition, Abbott was repeatedly accused by opponents of holding 'misogynist' or anti-women views and policies, culminating in a speech by former Prime Minister Julia Gillard which went viral worldwide.
Other low points of Abbott's stint as Australia's prime minister include the time he was widely denounced for giving Prince Phillip a knighthood, when he winked and smirked on a radio show while talking a call from an upset pensioner, and when he bemused Australians by taking a bite out of a raw onion on camera.
A prominent conservative in Australia, Abbott opposes same-sex marriage and was a main proponent of the country's controversial immigration policies.
Responding to Abbott's comments on Friday, Prime Minister Malcolm said both Australia and United States had a "vibrant democracy."
"I'm sure Mr Abbott has carefully read all of Donald Trump's policies before he made that comment," he said.