A 30-year-old Pakistani man was named on Sunday as the security guard killed in a weekend knife attack in a Sydney shopping mall, according to two local community groups.

The Australian Pakistani National Association and Ahmadiyya Muslim Community said Faraz Tahir was killed by a knife-wielding man who also killed five women.

On Sunday evening, members of the Muslim community held a silent vigil for the man, who is said to have moved to Australia last year.

"He quickly became an integral part of our community," a statement said.

The Australian Pakistani National Association encouraged the community to "stand together in solidarity, offering support and prayers to those grieving and affected by this heartbreaking loss".

As the attack unfolded on Saturday, online social media accounts falsely reported that the attack was linked to ideological or religious groups or events in the Middle East.

Police have named the assailant as 40-year-old itinerant man Joel Cauchi who was previously diagnosed with a mental health issue.

New South Wales police Assistant Commissioner Anthony Cooke said there was no evidence to suggest Cauchi was "driven by any particular motivation, ideology or otherwise".