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President Donald Trump on Twitter Sunday lashed out against citizens who'd taken to the streets to exercise their First Amendment rights.

While claiming that thousands of people who on Saturday demanded Trump finally release his full tax returns were "paid" protesters, Trump tweeted, "The election is over!"

"Someone should look into who paid for the small organized rallies," Trump tweeted a day after thousands of demonstrators took to the streets in more than 150 cities across the country.

An hour after wishing his 28 million followers a Happy Easter, Trump hailed his November win and called out those making his undisclosed tax history an issue.

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"I did what was an almost an impossible thing to do for a Republican-easily won the Electoral College! Now Tax Returns are brought up again?" Trump said on Twitter.

I did what was an almost an impossible thing to do for a Republican-easily won the Electoral College! Now Tax Returns are brought up again? — Donald J. Trump (@realDonaldTrump) April 16, 2017

Someone should look into who paid for the small organized rallies yesterday. The election is over! — Donald J. Trump (@realDonaldTrump) April 16, 2017

The president then followed up by repeating an unsubstantiated claim he's made before that some of the protesters against him were "paid," an allegation that became popular in some right-wing circles in the build up to the 2016 presidential election, before noting that the election was "over."

Trump himself used paid actors to pose as rally attendees during his campaign, and has talked at length about the election results since his victory while criticizing his former rival Hillary Clinton.

More than four months after winning the presidency, Trump continued to attack Clinton at a rally in Nashville, Tennessee, this March.

People participate in a Tax Day protest on April 15 in New York City. Stephanie Keith / Getty Images

The Tax Day protesters called for Trump to release his tax returns — something nearly all major presidential candidates have done since the 1970s — and call on lawmakers to represent their interests over those of major corporations.

Related: Tax Day Demonstrators Demand President Trump Produce Tax Returns

Trump and his administration have repeatedly dismissed calls for him to release his taxes, first claiming he couldn't because he was being audited, then saying the issue was more of interest to journalists and liberal politicians.

But a poll from the Pew Research Center in January found that more than two-thirds of all Americans believe the president has an obligation to release his tax returns.

This is not the first time the president has tweeted such accusations in the wake of major demonstrations against him and his policies. On Nov. 10, Trump tweeted that protests against his victory were "unfair" and said "professional protesters, incited by the media" were turning out in the streets.

Just had a very open and successful presidential election. Now professional protesters, incited by the media, are protesting. Very unfair! — Donald J. Trump (@realDonaldTrump) November 11, 2016

And on Feb. 3, in the midst of major protests against Trump’s first executive order on immigration, the president tweeted that "Professional anarchists, thugs and paid protesters are proving the point of millions of people who voted to MAKE AMERICA GREAT AGAIN!”

Professional anarchists, thugs and paid protesters are proving the point of the millions of people who voted to MAKE AMERICA GREAT AGAIN! — Donald J. Trump (@realDonaldTrump) February 3, 2017