Muslims who support Farhad Jabar's shooting of a NSW police worker should "stop messing with Australia and its society", according to the Grand Mufti of Australia.

"We refuse and reject any form of terrorist activities," said Dr Ibrahim Abu Mohamed, as Muslim leaders addressed the media in Sydney amid concerns the coming weekend could see ugly protests outside mosques.

Dr Mohamed said extremist preaching which set out to incite violence was not part of teachings or education in mosques across Australia.

"These misguided teachings are imported and not made in Australia," he said. "It comes from Sheikh Google, Sheikh Twitter and Sheikh Facebook."

The Grand Mufti's statement is in tune with Parramatta Mosque chairman Neil El-Kadomi.

Religious leaders from the Muslim and Christian communities including Dr Ibrahim Abu Mohamed (right), Grand Mufti of Australia, gather for a media press conference in Bankstown. Source: AAP

Mr Kadomi will, according to Fairfax media , tell his congregation during Friday's prayers: "If you don't like Australia, leave it."

One week ago schoolboy gunman Farhad Jabar, 15, visited Mr Kadomi's Parramatta mosque just before killing Curtis Cheng in a terror attack outside a police headquarters in Sydney's west.

Today concern was expressed about a "significant increase" of hate and threats of violence towards Australian Muslims.

Far right and nationalist groups are expected to carry out mass protests outside Parramatta Mosque today and in Canberra and Bendigo on Saturday.

"It is of great concern that there has been a significant increase in messages of hate of and threats of violence towards Australians of Muslim faith following the shooting," said a spokeswoman.

"Violent extremism is rare but important concern for everyone.

"Sadly a very, very small number of Australians of Muslim faith have chosen this path."

She said to define the actions of Farhad as religiously motivated was simplistic.

The drivers of violent extremism were complex and multi-faceted, she said.

She said home grown terrorists would likely be affected by "personal motives, individual history, psychological state, mental well-being, social situation, family context, personal relations, social identity and ideological attachment."

These factors, when combined with "misguided and deviant so-called religious teachings" become a dangerous recipe with serious consequences, she said.

Muslim leaders called for calm and further dialogue.

She said all stakeholders across the community assume responsibility: politicians, media, law and security enforcement, community leaders and religious educators.

"Religious educators have a significant role to play," she acknowledged.