General Motors Co.  (GM) is talking tariffs -- but the remarks are likely to be unwelcome to President Trump.

GM on Friday cautioned that U.S. tariffs on imported vehicles could lead to "a smaller GM" and could isolate U.S. businesses from the global market.

"Increased import tariffs could lead to a smaller GM, a reduced presence at home and abroad for this iconic American company, and risk less -- not more -- U.S. jobs," the Detroit-based automaker said in comments filed with the U.S. Commerce Department.

"Combined with the other trade actions currently being pursued by the U.S. Government -- namely the Section 232 Steel and Aluminum tariffs and the Section 301 tariffs against Chinese imports -- the threat of additional tariffs on automobile imports could be detrimental to our company. At some point, this tariff impact will be felt by customers," GM said. 

President Donald Trump and his administration announced in May that Commerce Secretary Wilbur Ross would investigate the need for protective measures on automobiles and automotive parts. The administration is reportedly considering a 25% tariff, and the president said in a Tweet on Tuesday that the study of tariffs on cars from the E.U. is finishing up.

....We are finishing our study of Tariffs on cars from the E.U. in that they have long taken advantage of the U.S. in the form of Trade Barriers and Tariffs. In the end it will all even out - and it won't take very long!

— Donald J. Trump (@realDonaldTrump) June 26, 2018

"We have received approximately 2,500 comments already and expect more by the midnight deadline [on Friday]," Ross said in a statement. "The purpose of the comment period and of the public hearing scheduled for July 19th and 20th is to make sure that all stakeholders' views are heard, both pro and con. That will enable us to make our best informed recommendation to the President."

Should the president impose a 25% tariff on imported vehicles, it could result in the loss of as much as two million vehicle sales for the U.S. auto industry, Jeff Schuster, senior vice president of forecasting at LMC Automotive, told TheStreet earlier this month.

Schuster's forecast assumes that the tariff would be in place for longer than a year and a majority of the tariff would be passed to consumers, leading to a loss of about 1 million annual vehicle sales. Should companies decide to pass on the entire 25% tariff to consumers, it could lead to a decline of about 2 million vehicle sales, or more than 10% of annual U.S. deliveries, Schuster said.

Shares of GM closed at $39.40, down about 2.8%.

-- This story has been updated to include a statement from Secretary Ross.