The bill, which was introduced late last year, extends control orders to juveniles to the age of 14, down from 16 years of age. It will also introduce a new offence of advocacy of genocide.
Attorney-General George Brandis said juveniles were in a different position to adults even though they were potentially just as dangerous.
Brandis will meet with state and territory attorneys-general in coming days to discuss the new laws.
The preventative detention change would match similar laws already in place for sex offenders and violent criminals in some states and comes after leaders agreed to the scheme at the meeting of the Council of Australian Government in Canberra in April.
Brandis said the change would be reviewed on a periodic basis.
"But I make no apology for the Government taking the view that if a person, having served a sentence of imprisonment for a serious crime, shows every indication of a willingness to repeat that crime, to reoffend as soon as they are released, they should remain behind bars," he told ABC radio.
He refused to comment on whether there were terrorists in jail now that would be kept behind bars as a result of the proposed laws, and said he was "reasonably confident" of the laws surviving a High Court challenge.
- AAP