Persuading people to spend money in a time of unpredictable tariffs is proving to be a complicated calculation for the $380 billion American advertising industry.

Should a retailer commit to holiday television commercials for toys manufactured by newly vulnerable trading partners? How do social media companies account for the potential disappearance of Chinese companies that have spent billions of dollars promoting their wares? How does an automaker pitch vehicles that may cost consumers thousands of dollars more than they did a year ago?

“You’re going to introduce uncertainty about how they make stuff, let alone what’s going to happen to consumers in terms of their propensity to buy?” said Brian Wieser, a veteran industry executive who runs Madison and Wall, a consulting firm. “That’s going to cause advertisers to really curtail their ad spending.”

Major companies were left in the lurch this month as the administration declared new tariffs, soon imposed them, reversed course a few days later and then doubled down on targeting China. Now, those advertisers feel “paralyzed,” said Jay Pattisall, a principal analyst at Forrester, a research firm. Several companies declined to elaborate on their marketing strategies for the coming months or said they were in “wait and see” mode.

“We are as in the dark about this as I think everybody else is,” Mr. Pattisall said. “It is such a volatile situation because the decision-making is quite volatile.”

Companies’ willingness to invest in marketing and promotion is often viewed as a proxy for the health of the global economy, a sort of indicator of whether gross domestic product might grow or contract. The tariffs could potentially trigger an economic domino effect, causing consumers to close their wallets, corporations to streamline their spending and marketing to take a back seat, several advertising experts said.