"I never thought anything like this could happen in America -never thought it could happen," Trump told an audience of several hundred donors, political allies and other supporters after returning to Mar-a-Lago, his beachfront mansion in southern Florida.
"The only crime that I've committed is to fearlessly defend our nation from those who seek to destroy it... It's an insult to our country," he claimed.
Hours earlier the 76-year-old former US president pleaded not guilty to 34 felony counts in a dramatic hearing in New York that transfixed the nation - and began the countdown to the first ever criminal trial of an American president.
Trump - the frontrunner in the race for the 2024 Republican nomination - said from a stage in an opulent gold-and-cream ballroom that "radical left" prosecutors were out to get him "at any cost."
Judge Juan Merchan said a trial could potentially start as soon as January - a month before the presidential primaries kick off - although Trump's lawyers have indicated they would want it pushed back to next spring.
The bizarrely celebratory mood in the room at Trump's Mar-A-Lago estate seemed at odds with the gravity of the day's events in Manhattan, with Trump reprising the applause lines that his supporters hear regularly at his rallies - and being rewarded with the same boisterous cheers and clapping.
Manhattan District Attorney Alvin Bragg is prosecuting Trump for cooking his company's books to hide payments he arranged for adult film actress Stormy Daniels days before the 2016 election, to cover up an alleged sexual encounter a decade earlier.
Manhattan prosecutors say Trump "repeatedly and fraudulently falsified New York business records to conceal criminal conduct that hid damaging information from the voting public during the 2016 presidential election."
A "statement of facts" released alongside the indictment included details of hush money payments to Daniels, Playboy model Karen McDougal and a former Trump Tower doorman claiming to have a story about a child Trump had out of wedlock.
Daniels was paid $130,000 by former Trump lawyer Michael Cohen, while McDougal and the doorman got $150,000 and $30,000 respectively from AMI, the publishers of supermarket tabloid the National Enquirer.
Bragg alleges that Trump and his allies "also took steps that mischaracterized, for tax purposes, the true nature of the payments."
Trump and his lawyers have accused Bragg of over-reaching in his characterization of the alleged misconduct.
Trump's former chief financial officer Allen Weisselberg is serving a five-month jail term for the same charge of falsifying business records.
The Kremlin on Wednesday said it did not want to comment on the indictment of former US President Donald Trump, accused of making payments to cover up embarrassing deals ahead of the 2016 presidential election.
"We will not comment on this," Kremlin spokesman Dmitry Peskov said after being asked a question by reporters.
"We do not believe we have the right to interfere in the internal affairs of the United States, and the United States is not entitled to interfere in our internal affairs," he said.
