"Don't judge President Trump by your theory about what [you think] might be his results," Ross said on CNBC's "Squawk Box." "Judge our trade policy by its results."
Earlier this month, Trump announced new tariffs on aluminum and steel, sparking fears of a possible trade war and sending the stock market into a tailspin.
The Commerce Department last month recommended imposing tariffs or quotas on foreign producers of steel and aluminum, citing national security. Ross said at the time that steel is important to U.S. national security and that current import flows are adversely affecting the steel industry.
"It's ludicrous that a car coming into the U.S. from abroad pays a 2.5 percent tariff; a car going from America to the EU pays a 10 percent tariff; a car going to China pays 25 percent," Ross said.
The countries "call themselves free traders," he added. "I don't see how you can be a free trader when you charge a tariff that's four to 10 times what we do on the exact same product."
While the EU threatens to fight back on Trump's tariffs, Ross on Monday met with German Economic Minister Peter Altmaier. The two released a statement saying, "We had a very constructive preliminary exchange on all relevant matters in our economic relationships with an eye toward relaxing trade tensions. We anticipate further discussions over the next few days."