The ruling comes as Elon Musk, the world's wealthiest man, is in the process of purchasing Twitter for $68b. The deal has raised questions about whether, Musk, a self-described free speech absolutist, would reinstate the former president.
Trump, who has continued to repeat lies about his 2020 election defeat in speeches, has started his own social network, Truth Social. He said last week that he wouldn't rejoin Twitter if given the chance.
The lawsuit had sought to reinstate Trump's account, which had roughly 89 million followers, and those of five others who claimed they were also censored by Twitter. The group had sought unspecified damages and class-action status on behalf of others removed from the platform.
Legal experts had predicted the lawsuit would fail but suggested Trump would milk it for political purposes. Trump's political action committee immediately began raising money after the lawsuit was announced last year.
The lawsuit had also sought a declaration that Section 230 of the 1996 Communications Decency Act was unconstitutional.
The act says providers such as Twitter can moderate services by removing obscene posts that violate their standards and cannot be held responsible for content posted by others.
Trump had only shown a "vague and speculative allegation" that he believed he would not have been banned if Twitter wasn't granted immunity by Section 230, Donato said.
Donato gave Trump another opportunity to amend his complaint. Trump's lawyer did not immediately respond to a request for comment.
