"America First now increasingly means America Alone," he told the RND media group. "That makes German businesses really worried."
For decades, the US has been a guarantor of free and fair world trade based on internationally accepted rules, but this policy is "obviously over for now," Schweitzer argued.
According to him, Trump is focusing only on American interests contradicting his previous statement that "America First does not mean America alone."
In this regard, he argued that it is always important to maintain dialogue, but stressed thatthe EU should "learn its lessons" and pursue a tougher stance.
"We are moving in the wrong direction if we automatically respond to new demands with concessions," Schweitzer concluded.
The move came after US President Donald Trump said that his country would exit the 2015 Iran nuclear deal on May 8. Along with the withdrawal from the agreement, the United States is restoring all sanctions against the Middle Eastern country, including secondary ones in relation to other countries that conduct business with Iran.