Brennan, a senior NBC and MSNBC analyst, is a frequent critic of Trump's.
President Donald Trump has decided to revoke former CIA Director John Brennan's clearance for access to classified information, he said in a statement read by press secretary Sarah Sanders on Tuesday.
The courtesy of allowing a former administration official to retain security clearance has been "outweighed by the risk posed by his erratic conduct and behaviour," Trump said in the statement. "Mr Brennan has a history that calls into question his objectivity and credibility."
"Mr Brennan has recently leveraged his status ... to make a series of unfounded and outrageous allegations, wild outbursts on the internet and on television about this administration," he added.
Brennan, who served as director of the clandestine intelligence agency under President Barack Obama, is a frequent critic of Trump's and a senior national security analyst for NBC News and MSNBC.
Specifically, Trump cited Brennan's denials that the CIA would access congressional computer files and statements that a dossier compiled by Christopher Steele about Trump during the 2016 campaign did not inform the agency's findings on Russian interference in the election.
For decades, former national security officials have retained classified clearance in part so that they can be consulted on closely held information by officials in ensuing administrations.