President Donald Trump on Friday said his administration will launch a trade probe into the EU that will cancel hefty fines levied against U.S. tech giants and likely result in a "substantial" tariff on the 27-member bloc.

Trump, in a lengthy Truth Social post, accused the EU of "'ROBBING' American Companies and, in turn, the American Taxpayer" as he raged over its recent $1 billion fine on Google for allegedly giving search priority to its own services.

"The European Union is at it again and, as usual, taking direct aim at GREAT American Companies!" Trump wrote in the post, which also railed against prior European fines against Apple, Meta and Amazon.

Trump claimed the latest penalty against Google was issued "without explanation." But the European Commission, the EU's executive branch, said in a press release Wednesday that the fines totaling 890 million euros were due to Google's alleged noncompliance with the bloc's Digital Markets Act, which aims to scrutinize Big Tech's practices.

Trump claimed the EU's behavior is "not going to continue during the Trump Administration."

"The United States of America is not a 'PIGGYBANK' for Europe, nor will we allow it to be!" he wrote.

Trump said the U.S. will "immediately" start an investigation under Section 301 of the Trade Act of 1974, which permits the imposition of tariffs in response to practices that are found to unfairly burden U.S. commerce.

The Trump administration has launched multiple probes using that tariff authority. Hours earlier, it imposed new duties between 10% and 12.5% on goods from more than 80 countries, including those in the EU, over alleged forced labor issues.

By Friday afternoon, a lawsuit challenging those tariffs had been filed in the U.S. Court of International Trade.

The suit, brought by the Liberty Justice Center on behalf of two small businesses, argues the federal government is improperly using Section 301 to effectively reinstate Trump's 2025 "liberation day" tariffs, which were the Supreme Court struck down earlier this year.

"The European Union will pay a very big price for this illegal and highly unethical conduct, which I have consistently warned them about," Trump warned in Friday's post, referring to its posture toward U.S. tech companies.

"The penalties will be entirely reversed and, we anticipate, a substantial TARIFF to be placed on them at the earliest possible moment," he wrote, adding, "Stay tuned!"