The hostage-taker as well as a male and female hostage were killed when New South Wales Police stormed the café in downtown Sydney.
The Australian-born media magnate tweeted two responses to the end of the siege, adding that “lone Wolves are the frightening danger”.
His comments drew an instant negative reaction on Twitter with many pointing out an insensitivity towards victims and their families.
The Australian Prime Minster Tony Abbott has also given his first reaction to the end of the siege saying that, “Australians should be reassured by how our security services dealt with this brush with terrorism.”
Abbott seemed to confirm the widely reported identity of the gunman as Man Haron Monis by saying that the dead hostage-taker was well-known to media and to police.
“As the siege unfolded yesterday he sought to cloak his actions with the symbolism of the Isil death cult,” Abbott said.
“Tragically there are people in our community ready to engage in politically motivated violence. The events in Martin Place also show that we are ready to deal with these people professionally with the full force of the law.”