"Considering empty political excuses, including those tied to security issues, unilateral and despotic US rules against Iranians, and arbitrary and lengthy arrests, accompanied by inhumane detention conditions, we ask Iranian citizens, especially members of the elite and scientists to refrain from visits to the US even for participating in scientific conferences and while having an invitation", the Ministry said.
On Saturday, Iran and the United States conducted an exchange of US-held Iranian scientist Massoud Soleimani and Xiyue Wang detained in Iran.
The United States has been consistently demanding from Iran to free all US citizens in its custody. US President Donald Trump in June of 2017 threatened Tehran with serious consequences if it did not release the prisoners. Trump's Iranian counterpart, Hassan Rouhani, has been saying that his government is ready to exchange prisoners with Washington.