WASHINGTON – Days after threatening to close the U.S. border with Mexico, President Donald Trump suggested Thursday that his administration would slap tariffs on autos long before it considered sealing the nation off from its southern neighbor.

“I don’t think we’ll ever have to close the border,” Trump said in the Oval Office.

Trump's statement marked a significant departure from his position last week, when he said there was a "very good likelihood" he would close the border this week. The White House faced sharp blowback from business groups and Republicans on Capitol Hill for the threat. A closure would disrupt the flow of roughly $1.5 billion in daily trade.

White House aides sought to soften the language through the week as the president prepared for a visit Friday to the border in California. Trump said earlier Thursday that he would give Mexico a year to halt the flow of illegal drugs coming into the USA. If the drugs didn’t stop, he said, the United States would impose tariffs on Mexican-made cars.

If that didn't work, Trump said, then the United States would close the Mexican border.

“That will be a very powerful incentive,” he said.

Trump insisted he wasn't bluffing.

"I will do it," he said. "I don't play games."

Trump’s remarks are the latest signal that the administration is toning down its rhetoric after days of relentlessly attacking Mexico over illegal border crossings.

During a trip to Florida last Friday, Trump warned there is a "very good likelihood" that he would close the border this week if Mexico didn’t do more to stem the influx of migrant families arriving from Central America.

By Tuesday, he softened his position, saying closing the border is still an option but he had seen signs that Mexico “has started apprehending more people.”

At a news conference in Washington, Mexico’s ambassador to the United States, Martha Bárcena, said her country would continue to cooperate with the Trump administration to address “the root causes” of migration.

“Migration will never be stopped,” she said at the Embassy of Mexico. “It is intrinsic to humanity. But what we can do is to do it in a regular way, in an orderly way that protects human rights.”

More:Fact check: Trump is wrong on Mexico's migrant apprehensions

Asked whether Trump’s policies and threats to close the border made things worse, Bárcena stressed the need for cooperation between the two countries.

"I respect him enormously – he’s the president of the United States," she said. "What I want to underline is that we want to cooperate. We want to continue to say to everybody that Mexico is willing to have a good relationship, that we need to work with the U.S. There are certain challenges, and one of them is migration. If we don’t cooperate, if we don’t see migration from a regional basis, we will not address the root causes of migration.”

Trump’s threat to close the border prompted objections from border state Republicans and business groups such as the U.S. Chamber of Commerce, which argued the move would damage the nation's economy.

In a statement Thursday, the chamber welcomed Trump's decision to keep the border open.

"Congress and the president should take this opportunity to enact border security and immigration reform. Congress should also ensure Customs and Border Protection officials receive the resources they need to reduce the excessive wait times affecting legitimate trade and travel across the border," said Neil Bradley, the chamber's executive vice president and chief policy officer.

Trump will visit the border Friday to tour a recently replaced section of border fence in California. It's the first such project completed under his presidency.

More:Plaque marking Trump's first 'border wall' section awaits his visit to Calexico