Mr Abbott's comments are the strongest yet by a major foreign leader on the Scottish independence debate and follow calls from US President Barack Obama to keep the union intact.
"As a friend of Britain, as an observer from afar, it's hard to see how the world would be helped by an independent Scotland," Mr Abbott told British newspaper The Times on Saturday.
"I think that the people who would like to see the break-up of the United Kingdom are not the friends of justice, the friends of freedom, and the countries that would cheer at the prospect ... are not the countries whose company one would like to keep."
Scotland goes to the polls on September 18 to decide whether to break away from the 307-year-old union with England.
A spokesman for Scottish First Minister Alex Salmond, who is leading the pro-independence campaign, said the Australian PM had "put his foot in it".
"Tony Abbott has a reputation for gaffes, but his bewildering comments have all the hallmarks of one of the Westminster government's international briefings against Scotland," he said.
"Many Australians, including the great number with close Scottish connections, will look on in bafflement at these remarks - Australia is a country that has gained its independence from Westminster and has never looked back."
A spokesman for Yes Scotland told the BBC: "These comments have echoes of Lord George Robertson's 'forces of darkness' speech in April which was widely ridiculed, even by No supporters, as one of the anti-independence campaign's most outlandish scare stories."
Mr Obama last month backed the union saying: "If it ain't broke, don't fix it."
Chinese Premier Li Keqiang, during a visit to London in June, also said he wanted a "strong, prosperous and united, United Kingdom".
Former Australian prime minister Kevin Rudd in March used an address at Oxford University to suggest Scotland's push for independence was flawed because it benefited from being part of the United Kingdom.
The Times on Saturday noted, however, that Mr Abbott's intervention was "the first time that the debate has been cast as one of western liberalism against its enemies".
Mr Abbott was in London earlier this week following a 24-hour visit to the Netherlands to thank those involved in identifying the victims of Malaysia Airlines flight 17.
In the English capital he met with UK Foreign Secretary Philip Hammond and Defence Secretary Michael Fallon to discuss the ongoing conflict in Iraq.
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