Comey said anyone who can see "moral equivalence" in protests by white supremacists and people who oppose them, who "lies constantly" and insists Americans believe it is "not fit to be president of the United States on moral grounds," Comey said in the interview on ABC.
The man who served as Trump's FBI director until the president fired him in May said the truth, the rule of law and integrity were "things [that] matter before any fights about policies" like whether the US should build a border wall or more strictly regulate the sale guns.
The interview was Comey's first ahead of the publication on Tuesday of "A Higher Loyalty: Truth, Lies and Leadership," his book about his short tenure in the Trump administration.
Comey spoke in the interview about a "dossier" containing raw intelligence on Trump's connections with Russians. He said it was raised in his first meeting with Trump shortly after the election in which Russian meddling in the US presidential election was discussed.