Australians, using the hashtag #illridewithyou on Twitter, are offering to accompany Muslims wearing religious attire on commuter trains or buses, with drivers ready to offer people a ride in their cars.
The campaign on Twitter has been launched over the fears that anti-Muslim sentiments may spread after the Arabic writing "There is no god but Allah; Muhammad is the Messenger of Allah" was seen on a black flag pressed against the window of the Lindt cafe earlier.
Several Muslim groups in the country have condemned self-proclaimed Iranian sheikh Man Haron Monis, who is allegedly responsible for the siege, in a statement describing the inscription on the flag as a "testimony of faith that has been misappropriated by misguided individuals".
CNN reported that at least two people died during the siege, but the report is yet to be officially confirmed.