Prime Minister Tony Abbott said it seemed they were trying to join "terror" groups in the Middle East.
They were stopped at Sydney International airport earlier this month.
It is a crime in Australia to fight for or assist militants on either side of the conflicts in the Middle East.
Mr Abbott said on Thursday the incidents proved "the continuing allure" of overseas "terror" groups.
The seven men, all believed to be connected to each other, tried to leave the country in two groups at separate times, said Immigration Minister Peter Dutton.
Speaking at a press conference, Mr Dutton said the first group of five men, in their 20s and 30s, were "offloaded" from a flight last week, interviewed and then searched by authorities.
Large amounts of cash were found in their luggage.
The next day, the same five men were again intercepted at the airport as they were trying to leave the country.
Mr Dutton said that in a separate incident, two men believed to be connected to the other five were intercepted at Sydney airport and searched and interviewed.
They also tried to depart again the next day.
The minister would not say if their passports had been confiscated or where the men were now.
He also would not confirm if any of the men were dual nationals or if they had been charged with any crime.
The government has drafted a bill that would strip dual nationals of their Australian citizenship if they engaged in terrorism.
Australia is on high alert for attacks by radicalised Muslims, including those returning home from fighting in the Middle East.
In December last year, the country specifically banned travel to Syria's Raqqa province, which is held by the so-called Islamic State group (IS).
It means anyone entering the area could face up to 10 years in prison unless they have a legitimate reason, including family visits, journalism or aid work.
Australian authorities have stopped seven young Australians from leaving the country, fearing they planned to fight in the Middle East.