"I never thought anything like this could happen in America," he told supporters at his Mar-a-Lago resort on Tuesday evening after flying back from his historic court appearance in New York City.
The Republican accused Democrats of spying on his campaign and listed what he claimed were "fraudulent investigations" of his conduct while in office, such as the probe into Russian interference in the 2020 election.
He called the 34 felony counts of falsifying business records brought by Manhattan District Attorney Alvin Bragg, a Democrat, "massive election interference at a scale never seen before in our country".
Trump returned to Florida after pleading not guilty in a Manhattan court on Tuesday afternoon, where prosecutors accused him of orchestrating payments to two women before the 2016 US election to suppress publication of their sexual encounters with him.
They allege Trump - the first sitting or former US president to face criminal charges - falsified business records to conceal a violation of election laws during his successful 2016 campaign.
The two women were adult film actor Stormy Daniels and former Playboy model Karen McDougal.
Prosecutor Chris Conroy said: "The defendant Donald J Trump falsified New York business records in order to conceal an illegal conspiracy to undermine the integrity of the 2016 presidential election and other violations of election laws."
While falsifying business records in New York is punishable by no more than one year in prison, it is punishable by up to four years when done to advance or conceal another crime, such as election law violations.
Prosecutors said Trump, 76, made a series of threatening social media posts, including one threatening "death and destruction" if he was charged. The judge asked the parties to "please refrain from making statements that are likely to incite violence or civil unrest".
Trump, the frontrunner in the race for the Republican nomination in 2024, said nothing as he entered the courtroom or when he left roughly an hour later.
Justice Juan Merchan set the next hearing for December 4. Legal experts say a trial might not begin for a year, and indictment or even a conviction will not legally stop Trump running for president.
"We're going to fight it hard," Todd Blanche, a lawyer for Trump, told reporters after the arraignment, adding that Trump was frustrated, upset and angry about the charges.
Manhattan District Attorney Alvin Bragg, a Democrat who has been accused by Trump and other Republicans of targeting him for political reasons, defended the charges.
"We today uphold our solemn responsibility to ensure that everyone stands equal before the law. No amount of money and no amount of power changes that enduring American principle," Bragg told a news conference.
The Manhattan grand jury convened by Bragg heard evidence about a $US130,000 ($A193,000) payment made to Daniels in the waning days of the 2016 presidential campaign. Daniels has said she was paid to keep silent about a sexual encounter she had with Trump at a Lake Tahoe hotel in 2006.
The former publisher of the National Enquirer, David Pecker, offered to look out for negative stories during Trump's presidential campaign, prosecutors said. American Media Inc, its parent company, paid McDougal $US150,000 to buy the rights to her story but then kept it secret.
It also paid a former Trump Tower doorman $US30,000 to buy the rights to an untrue story about a child Trump had allegedly fathered out of wedlock.
Trump's former lawyer Michael Cohen says he co-ordinated with Trump on payments to Daniels and McDougal. Trump has denied having had sexual relationships with either woman, but has acknowledged reimbursing Cohen for his payment to Daniels.
Trump's reimbursement cheques to a lawyer for the suppression payments falsely stated the money was for a "retainer agreement", prosecutors said. The indictment accused Trump of falsifying his real estate company's books with intent to defraud.
Trump supporters and detractors before the arraignment were separated by barricades set up by police, though there were some confrontations.
