The move comes days after the European Commission fined Google €890m for allegedly abusing its market position by favouring its own services over competitors.
The EU has also investigated other US tech giants, including Apple, Meta and Amazon, under regulations designed to increase competition in digital markets.
In a post on Truth Social, Trump accused European regulators of unfairly targeting American businesses and demanded that fines against US companies be reversed.
The White House chief wrote: "The United States of America is not a ‘PIGGYBANK’ for Europe, nor will we allow it to be!"
The president said the US would launch a Section 301 investigation into the EU, a process that allows the US Trade Representative to examine alleged unfair trade practices. He added that Washington was considering "a substantial TARIFF" in response.
The tariff threat follows Trump’s announcement of new import duties on dozens of trading partners, including the EU, UK and China. He also previously warned that countries introducing digital services taxes on American technology firms could face a 100 per cent tariff.
Google defended its position, saying it had worked to comply with the EU’s Digital Markets Act while raising concerns about the impact of recent regulatory decisions.
The tech behemoth's spokesperson Jose Castaneda said: "We appreciate the engagement by the administration and US government."
Trump also claimed Apple, Meta and Amazon had received billions of dollars in EU fines, although the figures cited did not match publicly available records.
Representatives for the companies and the European Commission have been contacted for comment.
The dispute highlights growing tensions between Washington and Brussels over technology regulation. The EU argues that laws such as the Digital Markets Act are needed to prevent dominant platforms from restricting competition, while US officials have repeatedly accused Europe of unfairly targeting American firms.
Several leading technology companies have faced European penalties in recent years.
Meta has received fines related to privacy and competition rules, while Amazon has previously agreed to change business practices following EU scrutiny.
The latest clash could further strain US-EU relations as both sides negotiate trade and technology policies.
