“Apple will not be given Tariff wavers, or relief, for Mac Pro parts that are made in China. Make them in the USA, no Tariffs!” Trump said in a tweet on Friday.

The Cupertino, California-based technology giant has asked the Trump administration to exclude components that make up the forthcoming Mac Pro high-end desktop computer from import tariffs, weeks after planning to relocate production of the line to China from Texas.

Apple shares dipped briefly following the tweet and mostly recovered. They were up less than 1% at 10.16am in New York.

Trump has previously promised relief if companies can show that parts or products can only be obtained in China aren’t “strategically important” to Chinese industrial programs, or that the duties would cause “severe economic harm.”

Trump has tweeted that companies won’t face a tariff if they make their goods “at home in the USA.”