Buttrose said in a statement that the raid was "unprecedented" and "clearly designed to intimidate", reports Efe news.
The raid on Wednesday was linked to a series of reports by the ABC, known as "The Afghan Files" on alleged war crimes committed by Australian elite troops in Afghanistan, which include incidents that took place between 2011 and 2013, such as the killing of unarmed people and children.
It came a day after the police also searched the home of News Corp journalist Annika Smethurst in Canberra due to her information about the Australian government's plans to give more powers to intelligence agencies to spy on the citizens of their country.
"Raids on two separate media outfits on consecutive days is a blunt signal of adverse consequences for news organisations who make life uncomfortable for policy makers and regulators by shining lights in dark corners and holding the powerful to account," Buttrose said.
The ABC Chair made these remarks after meeting with the Minister for Communications, Cyber Safety and the Arts, Paul Fletcher on Thursday, in which she asked him for assurances that the broadcaster would not be subject to similar raids in the future, which he refused to provide.
"I will fight any attempts to muzzle the national broadcaster or interfere with its obligations to the Australian public," Buttrose added, pointing out that "independence is not exercised by degrees. It is absolute".
On Thursday, Prime Minister Scott Morrison defended the legality of the raids but distanced the government from the police action while reiterating his administration's commitment to press freedom.
The police action was also criticized by the Media, Entertainment and Arts Alliance, Australia's media union, which said that the raids "are about intimidating journalists and media organisations because of their truth-telling".
They are about more than hunting down whistle blowers that reveal what governments are secretly doing in our name, but also preventing the media from shining a light on the actions of government."
Since 2014, Australia has enacted a series of laws, which criminalize the disclosure of information linked to state interests, classify new crimes of espionage and allow access to the meta-data of citizens, among others.
( With inputs from IANS )