President Donald Trump's concerns about trade with China are fair, but his approach may not be, former U.S. Trade Representative Michael Froman told CNBC on Monday.

"We ought to stipulate that the concerns that the Trump administration has raised about China are real and legitimate," said Froman, who was former President Barack Obama's principal advisor, negotiator and spokesman on international trade and investment issues.

"I think the question is whether the Trump administration is approaching it in a way that's most likely to achieve success," he said in "Squawk Box" interview.

In a tweet early Monday, Trump called out China again for what he has called unfair trade practices by the world's second-largest economy.

@realDonaldTrump: When a car is sent to the United States from China, there is a Tariff to be paid of 2 1/2%. When a car is sent to China from the United States, there is a Tariff to be paid of 25%. Does that sound like free or fair trade. No, it sounds like STUPID TRADE - going on for years!

The president unveiled a list of Chinese imports last week that his administration aims to target as part its crackdown on China. Shortly after the announcement, China announced plans for additional tariffs.

China's Foreign Ministry blamed the United States on Monday for trade friction and said it was impossible for negotiations to take place under current conditions.

Commerce Secretary Wilbur Ross said last week that China's new tariffs on 106 products do not represent a threat to the United States.

China's tariffs "amount to about three-tenths of a percent of our GDP. So, it's hardly a life-threatening activity," Ross told CNBC. "It's relatively proportionate to the tariffs we put on based on the intellectual property."

Still, the possibility of a U.S.-China trade war has sent the stock market into a tailspin in recent weeks. During a "Fox News Sunday" interview, White House chief economic adviser Larry Kudlow tried to calm trade war fears but added that Trump was "not bluffing" on tariffs.

In an earlier trade move to pressure China and jump-start NAFTA talks with Canada and Mexico, Trump last month announced broad tariffs on steel and aluminum. The administration eventually gave Canada and Mexico a pass, pending a successful reworking of the 1994 North American Free Trade Agreement.

Froman, a fellow at the Council on Foreign Relations, said Monday it's possible the Trump administration is attempting to have a favorable outcome on NAFTA so it can focus on China.

The ministers responsible for the NAFTA renegotiation met Friday, and said progress has been made.

"I think they'd like to clear the decks," said Froman, who served in Obama's Cabinet as the U.S. trade representative from June 2013 to January 2017. "But to be frank, I think they're running out of time. Because right now, they're just talking about an agreement in principle."