In a statement on Wednesday, Mousavi slammed Trump, who said Afghanistan “would be wiped off the face of the Earth” if he wanted to win the war in the country.
The Iranian spokesman described the remarks as “racist and unacceptable” and said they endanger international peace and security.
“The Islamic Republic of Iran sides with the resistant nation and the government and intellectuals of the brotherly and neighboring country of Afghanistan,” he added.
Trump on Monday suggested that he could put an end to the Afghanistan war in a week, but that it would cost millions of lives and wipe the country “off the face of the Earth.”
“If we wanted to fight a war in Afghanistan and win it, I could win that war in a week. I just don't want to kill 10 million people,” Trump said, seated beside Pakistani Prime Minister Imran Khan at the White House.
“I have plans on Afghanistan, that if I wanted to win that war, Afghanistan would be wiped off the face of the Earth. It would be gone. It would be over in -- literally, in 10 days, and I don't want to do -- I don't want to go that route.”