Robert F. Kennedy Jr. has made censorship — specifically, claims that the government, news media and tech platforms have tried to stifle his message — a cornerstone of his independent presidential campaign.

This weekend, Mr. Kennedy got more fodder for his argument when Facebook and Instagram blocked a link to a new, sleekly produced 30-minute ad supporting his candidacy. The link appeared to have been blocked from Friday late afternoon until Saturday around midday.

Meta, which owns both platforms, called the episode a mistake. Andy Stone, a spokesman for Meta, said the link had been incorrectly flagged as spam. “It was mistakenly blocked, and it was corrected within a few hours” after the issue was discovered, Mr. Stone said.

Tony Lyons, a founder of American Values 2024, the super PAC that paid for the ad, did not immediately provide a comment.

The ad, which is narrated by the actor Woody Harrelson and takes the form of an infomercial, was produced by Jay Carson, an informal adviser to Mr. Kennedy who is also a Hollywood screenwriter and a former top aide to Hillary Clinton.

The ad seeks to introduce Mr. Kennedy to a broad audience, portraying him as a crusader for a clean environment, good government and American values, free from corporate influences that he says have corrupted the major political parties and endangered Americans’ health.

The ad also seeks to confront, in a lighthearted way, criticisms of Mr. Kennedy. It opens with his reading aloud from press clippings that describe him as, among other things, “clearly disturbed,” “so crazy,” “a walking, talking conspiracy theory” and a “humorless bully.”

After the video’s release on Friday, Instagram and Facebook users began to report that posts with the link had been removed because it appeared to violate the platforms’ terms of service, according to screenshots either shared with The New York Times or posted online by supporters and the campaign.

On Saturday, the campaign released a TikTok showing a compilation of error messages. The campaign also sent out a fund-raising email to supporters, urging them to document what it described as “election interference.” In a post on Facebook that afternoon, Mr. Kennedy called the ad “the Bobby Kennedy video Facebook doesn’t want you to see.”

In the ad, Mr. Kennedy traces his evolution as the scion of a storied American political dynasty and describes his struggles with heroin addiction after he began his legal career more than four decades ago.

Sobriety got him back to the outdoors, he says, and pushed him to a career as an environmental lawyer.

That work at first earned him accolades, highly paid speeches, glossy magazine spreads and photo shoots with celebrities like Oprah Winfrey and Julia Roberts. But then, as the ad recounts, he turned his attention to theories about the supposed dangers of childhood vaccinations, and he found that major news media outlets that once celebrated him now painted him as a dangerous purveyor of conspiracy theories.

The ad dwells on Mr. Kennedy’s physical fitness — at one point Mr. Harrelson intones: “He can do 25 pull-ups in one go. I can do three.” Mr. Harrelson is never shown in the ad, but his voice is unmistakable. (“You need to rock the damn boat,” he says at another point, “because the system doesn’t just need tweaks at the margins, it actually needs a wholesale rethinking.”)

Mr. Kennedy’s wife, the actress Cheryl Hines, is interviewed in the ad, and Jack Dorsey, a founder of Twitter, appears briefly to praise him.

Mr. Kennedy’s skepticism of vaccinations — which includes disproved claims linking some childhood vaccines to autism — and his allegations of government overreach gained a wider audience during the coronavirus pandemic, even though Instagram, Facebook, YouTube and other platforms disabled his account and others that promoted what the companies called medical misinformation.

In the ad, he explains his stance on Covid-19: “I feared that a rushed Covid vaccine wouldn’t be as safe or as effective as we were promised. And I also felt that lockdowns were going to do more harm than good, especially to small businesses and to children. But when I made those arguments publicly, I was silenced.”

Mr. Kennedy’s social media accounts were reinstated last year after he became a presidential candidate.