The administration is now deciding which Chinese goods to tax as part of its next round of tariffs. A public comment period on a proposed list of products, from fish to feathers to fitness trackers, ended on Thursday, and officials said they planned to take the comments, plus those made during six days of hearings, into account before deciding which products to hit.

In a letter filed with the Trump administration this week, Apple warned that the proposed tariffs would affect a wide range of its products, including watches, headphones, chargers and adapters.

“Our concern with these tariffs is that the U.S. will be hardest hit, and that will result in lower U.S. growth and competitiveness and higher prices for U.S. consumers,” the company wrote in a letter to Robert E. Lighthizer, Mr. Trump’s top trade negotiator, that was made public on Friday.

The imposition of new tariffs is supposed to go through a rigorous government investigation into whether the levies are warranted, including public feedback on how the move would affect American industry. But Mr. Trump continues to dangle the prospect of additional duties in a casual manner.

“The notion that the president is going to add an extra $267 billion worth of tariffs is grossly irresponsible and possibly illegal,” said Jose Castaneda, a spokesman for the Information Technology Industry Council, suggesting that the administration had not conducted the necessary investigation to justify such a decision.

Mr. Trump has previously said he is prepared to tax nearly all Chinese goods that come into the United States. Still, the threat of further tariffs rattled stock markets, in part because China has said it plans to retaliate against any American trade barriers.

For now, talks between the world’s two largest economies remain stalled.

“Trump has a strong incentive to strike some sort of deal with China that will allow him to claim victory as a deal maker,” said Eswar Prasad, a trade policy professor at Cornell University. “However, notwithstanding any negative blowback from Trump’s domestic constituents, it increasingly looks like the off-ramp from this trade war is unlikely to materialize before the midterm elections in the U.S.”