It's a sharp contrast to earlier days in Trump's tenure when tech executives were occasional celebrity guests at the White House, serving as a fresh indication of the president's escalating battle with Big Tech.
Now, Trump regularly accuses the big social media platforms of suppressing conservative voices. He has suggested the companies may be acting illegally and should be sued by U.S. regulators.
White House spokesman Judd Deere said the White House conference on Thursday would bring together "digital leaders for a robust conversation on the opportunities and challenges of today's online environment."
But Google, Facebook and Twitter weren't invited, their representatives confirmed. And their leaders may be more likely to turn up Thursday at an annual media industry conference in Sun Valley, Idaho, a venue oriented more toward high-stakes deal-making than reflections on perceived bias in online communications.
The White House had no comment on why top tech officials weren't invited or on whether the conference was deliberately scheduled to overlap with the meeting in Idaho.
Among the conservative organizations that are expected to participate in the White House meeting: Turning Point USA; PragerU, short for Prager University, which puts out short videos with a conservative perspective on politics or economics; and the Washington think tank Heritage Foundation.
Trump and some supporters have long accused Silicon Valley companies of being biased against them. Accusations commonly leveled against the platforms include anti-religious bias, a tilt against those opposed to abortion and censorship of conservative political views. While some company executives may lean liberal, they have long asserted that their products are without political bias.
Representatives for Facebook, Google and Twitter declined to comment specifically on Thursday's meeting. But the Internet Association, the industry's major trade group representing Facebook, Google and dozens of other companies, said the internet "offers the most open and accessible form of communication available today."
Its members' platforms "don't have a political ideology or political bias," the group's president and CEO Michael Beckerman said in a statement. He added that the companies "succeed and grow by building a broad user base regardless of party affiliation or political perspectives."
Twitter spokeswoman Katie Rosborough, in a statement, said "We enforce the Twitter rules impartially for all users, regardless of their background or political affiliation. We are constantly working to improve our systems and will continue to be transparent in our efforts."
Trump has played to conservative concerns about bias on other issues. In March, he signed an executive order requiring U.S. colleges to protect free speech on their campuses or risk losing federal research funding. The order cheered those who said universities were attempting to silence some conservative students and speakers. But critics called the order unnecessary.
The president himself was dealt a setback Tuesday in his legal battle against Twitter, his favored means of communicating. A federal appeals court in New York City ruled that the president can't ban critics from his Twitter account, saying the First Amendment calls for more speech, rather than less, on matters of public concern.
Trump has an estimated 61 million followers on Twitter. He has accused Twitter of making it "very hard for people to join me" and "very much harder for me to get out the message."
Thursday's conference raised questions about whether Trump would use the forum to signal tough actions ahead by his administration against the big companies in the areas of competition and privacy.
Big tech companies already are under closer scrutiny than ever by regulators and in Congress following a stream of scandals including Facebook's lapses opening the personal data of millions of users to Trump's 2016 campaign. A bipartisan push for new data privacy legislation has emerged in Congress. Regulators at the Justice Department and the Federal Trade Commission are pursuing antitrust investigations of Facebook, Google, Apple and Amazon. The House Judiciary Committee has opened a bipartisan probe of the tech giants' market dominance.
A growing number of lawmakers and some Democratic presidential candidates are talking about tighter regulation of a customarily freewheeling industry or even breaking up the big companies.
But if Trump is looking for the participating conservative groups to support government action to bring the companies in line on perceived social media bias, he may be disappointed.
Rob Bluey, vice president for communications at the Heritage Foundation, said that "if the government were to get involved, it would lead to more problems." He said market pressures can produce positive changes.
Turning Point USA keeps a list of college professors who it says discriminate against students with conservative views. "I think there will be some form of equilibrium" between the social media platforms and Americans who hold right-of-center views, Charlie Kirk, the group's executive director, said Tuesday. "Hopefully these companies can self-correct."
"Voters will be constructing their choices for 2020" based largely on information from social media, Kirk said.
Trump said last week on Fox News that Google, Facebook and Twitter "are fighting me hard right now, which is incredible because I think the Democrats want to shut them up and, frankly, so do a lot of the Republicans want to shut them up."
Asked whether tech companies may be acting illegally and whether the Justice Department should determine that, Trump replied, "Well, they could be and I don't want to even say whether or not they're doing something, but I will tell you, there are a lot of people that want us ... to take action against Facebook and against Twitter and, frankly, against Amazon."
Trump told Fox Business Network's Maria Bartiromo last month that he doesn't know if what the companies are doing is illegal but added, "I tell you what, they should be sued because of what's happening with the bias."
Associated Press writer Kevin Freking contributed to this report.