The Turkish lira fell 13 percent to 6.51 per dollar.
"We will not surrender", Erdogan asserted.
"Turkey expects other member countries to abide by global rules", the country's trade ministry said in a statement.
"We will say goodbye to those, who sacrifice its strategic partnership and alliance with a country of 81 million people on the altar of its relations with terror organizations", he said. USA stocks were also rattled.
Turkey and the USA are now experiencing rocky relations following Washington's imposition of sanctions on Interior Minister Suleyman Soylu and Justice Minister Abdulhamit Gul for not releasing American Pastor Andrew Brunson, who faces terrorism charges in Turkey.
The president, who says a shadowy "interest rate lobby" and Western credit ratings agencies are attempting to bring down Turkey's economy, appealed to his countrymen's patriotism.
"These are the bullets, cannonballs and missiles of an economic war waged against our country", he said. "Failure to reverse this trend of unilateralism and disrespect will require us to start looking for new friends and allies", Erdogan said.
It said it would support steel and aluminium exporters on all worldwide platforms, and the USA remained an important trade partner.
Turkey also warned there would be retaliation against the US' imposition of the tariffs.
Turkey wants the United States to extradite cleric Fethullah Gulen, a Pennsylvania-based cleric who Turkish authorities say masterminded the coup attempt in which 250 people were killed.
"If you advance upon us by the dollar, we will look for other means to carry on our business", he added. Gulen denies the allegation.
Andrew Brunson has been in Turkish custody since 2016, when he was arrested on charges of terrorism and support of a group held responsible for an attempted coup of Turkish President Recep Tayyip Erdogan.
His cause resonates with Trump's Christian conservative supporters, who could be influential as Republicans seek to retain control of Congress in midterm elections in November.
Jay Sekulow, an attorney for Trump who is also representing Brunson's family, told talk-show host and political commentator Sean Hannity's radio program on Friday: "We're close to getting a resolution in that case". "The U.S. has to rehabilitate its addiction to sanctions & bullying or entire world will unite - beyond verbal condemnations - to force it to".