In the attack on Saturday, five of the six people killed and the majority of the 12 injured were women. Police said on Monday they had finished taking physical evidence at the Westfield Bondi Junction mall.
"It's obvious to me, it's obvious to detectives that seems to be an area of interest that the offender focused on women and avoided the men," New South Wales state Police Commissioner Karen Webb told the Australian Broadcasting Corp.
"The videos speak for themselves, don't they? That's certainly a line for inquiry for us."
Witnesses described how attacker Joel Cauchi, 40, wearing shorts and an Australian national rugby league jersey, ran through the mall with a knife. He was killed by Inspector Amy Scott, who confronted him solo while he was on the rampage.
Police have said Cauchi had mental health issues in the past and there was no indication ideology was a motive.
Violent crimes such as Saturday's stabbing are rare in the country of about 27 million people, which has some of the world's toughest gun and knife laws.
Prime Minister Anthony Albanese said "the gender breakdown ... was concerning" when asked on ABC Radio if it was a gender-motivated attack.
"The New South Wales Police have said they're looking at that as part of the investigation," he said.
The only man who was killed by Cauchi during the attack was a mall security guard.
The Australian national flag is flying at half-mast across the country, including at the Parliament House and Sydney's Harbour Bridge, in honour of the victims. Sydney Opera House's sails will be lit with a black ribbon on Monday evening.
Chinese state TV reported on Sunday that one Chinese citizen was among those who had died in the attack, without revealing the identity of the victim, adding that another Chinese citizen was injured.
