Cusack, who has starred in blockbusters like "2012", "High Fidelity" and "Serendipity", took to Twitter and flooded his entire social media account with a series of tweets about the events that has shaken India since last evening.
The Hollywood star also shared several videos of the attacks that were tagged as "Video from the assaults".
In one tweet he shared quotes of author Arundhati Roy on the current situation in the state.
He wrote in one thread: "Fascists in India trying to set students against each other -
To cover for economic collapse of demonetization but they are standing together in solidarity with their Muslim brothers and sisters - This is fascism everywhere- them or us Arundhati Roy pic."
In another Cusack wrote: "Reports from Delhi are it was a war zone last night - Fascism is not a joke - we use the word with the understanding it's deadly."
He even commented on India's economy.
"Indian economy in ICU chaos civil war," he said.
Cusack's support comes in the wake of severe protests against Citizenship (Amendment) Act continued in different parts of the country, including Delhi, Assam, Hyderabad, Aligarh and Kolkata.
The contentious Act passed in the winter session of Parliament seeks to grant Indian citizenship to refugees from Hindu, Sikh, Buddhist, Parsi and Christian communities coming from neighbouring countries like Pakistan, Afghanistan, and Bangladesh.
( With inputs from IANS )