WASHINGTON — The Trump administration said on Wednesday that it would investigate whether a French plan to impose a tax on American technology giants like Facebook and Google amounts to an unfair trade practice that could be punished with retaliatory tariffs, escalating its global trade fight.

The investigation, to be carried out by the United States trade representative, is the latest attempt by the Trump administration to shelter American companies, particularly in tech, by taking a more aggressive stance toward allies’ trading practices.

It is likely to further stoke tensions with the European Union, which President Trump has already threatened with auto tariffs and criticized for selling more goods to the United States than it purchases. Mr. Trump has repeatedly said the European Union is worse than China when it comes to trade practices and has lashed out at its top antitrust regulator, Margrethe Vestager, saying she has unfairly targeted Google, Apple and other American companies.

The American action announced on Wednesday is aimed at France, which has moved independently from the European Union to seek a tax on technology companies.