President Trump warned major U.S. technology companies Tuesday that they "better be careful" about political bias in search results and social media policy.

"I think Google has really taken advantage of a lot of people. And I think that's a very serious thing and that's a very serious charge," Trump told reporters in the Oval Office, following a series of morning tweets on the topic.

"I think what Google and what others are doing, if you look at what is going on at Twitter, if you look at what is going on in Facebook, they better be careful because you can't do that to people. You can't do it," he said.

[Also read: Trump to social media services: 'Let everybody participate, good & bad']

Trump did not say whether he would recommend new policies or penalties for tech companies, but said "we have literally thousands and thousands of complaints coming in."

"I think that Google and Twitter and Facebook, they're really treading on very, very troubled territory. And they have to be careful. It's not fair to large portions of the population," he said.

As of Friday, an administration official said there were no internal moves to craft a regulatory or legislative response to alleged bias by social media platforms, which this month banned or suspended prominent nonmainstream commentators. Separately, some conservatives allege "shadow-banning" by Facebook, meaning their posts aren't displayed to followers.

In recent public remarks and statements on Twitter, Trump has accused social media companies of "censorship," and on Tuesday morning, he expanded his criticism to Google, saying search results were skewed in favor of hostile publications.

"Google search results for 'Trump News' shows only the viewing/reporting of Fake News Media. In other words, they have it RIGGED, for me & others, so that almost all stories & news is BAD. Fake CNN is prominent. Republican/Conservative & Fair Media is shut out. Illegal?" he wrote on Twitter.

Trump continued: "96% of [...] results on 'Trump News' are from National Left-Wing Media, very dangerous. Google & others are suppressing voices of Conservatives and hiding information and news that is good. They are controlling what we can & cannot see. This is a very serious situation-will be addressed!"

Google denied political bias in a statement, saying: "When users type queries into the Google Search bar, our goal is to make sure they receive the most relevant answers in a matter of seconds. Search is not used to set a political agenda and we don't bias our results toward any political ideology."

The company continued: "Every year, we issue hundreds of improvements to our algorithms to ensure they surface high-quality content in response to users' queries. We continually work to improve Google Search and we never rank search results to manipulate political sentiment."