He also refused to take a question from a CNN reporter.
Trump called BuzzFeed a "failing pile of garbage," arguing the online media outlet "will suffer the consequences." A day earlier, BuzzFeed published a 35-page dossier of unsubstantiated allegations of Russian information-gathering on Trump.
At the news conference, Trump took CNN to task for "going out of their way to build it up," then refused to take a question from CNN's Jim Acosta.
"Your organization is terrible," the president-elect told Acosta at the nationally televised news conference at Trump Tower. "I am not going to give you a question, you're fake news."
A spokesperson for CNN released a statement, arguing that the network's reporting on the matter differed from BuzzFeed:
"CNN's decision to publish carefully sourced reporting about the operations of our government is vastly different than Buzzfeed's decision to publish unsubstantiated memos. The Trump team knows this. They are using Buzzfeed's decision to deflect from CNN's reporting, which has been matched by the other major news organizations. ... We made it clear that we were not publishing any of the details of the 35-page document because we have not corroborated the report's allegations."