Rowling is one of the authors and notable faces who have expressed their disbelief after Sir Salman was stabbed on stage in New York state.
The Indian-born British author, 75, whose writing prompted death threats from Iran in the 1980s, was due to deliver a lecture at the Chautauqua institution when the incident occurred , leaving him with an apparent stab wound to the neck.
He is on a ventilator and may lose an eye and has nerve damage in his arm and liver, according to the New York Times.
On Friday, New York State Police named the alleged assailant as Hadi Matar, 24, of Fairview, New Jersey, who was arrested after the incident.
Since the suspect was identified, people on social media have speculated whether the attack was linked to Iran’s former leader Ayatollah Khomeini, who had previously issued a fatwa calling for his death.
The call was made after the publication of his book The Satanic Verses, banned in Iran since 1988, as many Muslims consider it blasphemous.