President Donald Trump has frequently said negative things about Amazon (AMZN) and its founder and CEO Jeff Bezos, and that trend continued over the weekend. In an interview with Axios on Sunday, Trump reiterated his interest in potentially taking antitrust action against multiple major tech firms, including Amazon.

Trump specifically said he has heard “a lot of people talking about monopoly” when it comes to Amazon, Facebook (FB) and Google (GOOG), in particular. In the interview, he said his administration could potentially take antitrust action against those companies, but stopped short of actually committing to it.

GettyImages-697899732 The president hinted at antitrust action against tech companies again. US President Donald Trump (L) and Microsoft CEO Satya Nadella (C) listen to Amazon CEO Jeff Bezos (R) during an American Technology Council roundtable at the White House in Washington, DC, on June 19, 2017. Photo: Nicholas Kamm/AFP/Getty Images

“We are looking at [antitrust] very seriously,” Trump told Axios. “Look, that doesn't mean we're doing it, but we're certainly looking and I think most people surmise that, I would imagine."

Trump vaguely threatening companies like Amazon with antitrust legislation is not new. The president has consistently accused Amazon of failing to pay taxes, even though he once called himself smart for doing the same thing. Additionally, he has maintained a feud with Bezos, as Trump regularly criticizes the tech billionaire’s ownership of the Washington Post.

Bezos purchased the Post for $250 million in 2013.

The president has accused the newspaper of spreading “fake news” and even called for one reporter to be fired due to content that was critical of him.

Still, Trump told Axios he is “not looking to hurt these companies.” He called them “great companies” and said he wants them to do well. Once again, he criticized the European Union for issuing a large fine against Google earlier this year on antitrust grounds. He said the E.U. “takes a lot of money out of our companies.”

Shares of Amazon, Facebook and Google’s parent company Alphabet all fell in Monday trading.