The US Customs and Border Control (CBP) detained at length and questioned the Iranians who were returning to the US after attending a concert on Saturday in the Canadian city of Vancouver, Press TV quoted the Council of American-Islamic Relations (CAIR) as saying.
Other Iranians, who have been residing in the United States for years, were denied entry to the US.
"Many more are turned around at the border and refused the opportunity to enter the United States due to a lack of capacity for Customs and Border Patrol to detain them," CAIR's Washington chapter said in a news release.
In a tweet, Washington Congresswoman Pramila Jayapal said she was "deeply disturbed" by the reports of the detentions.
The executive director of CAIR Washington said the reports of detentions "are extremely troubling and potentially constitute illegal detentions of United States citizens."
The detentions come amid growing tensions between the US and Iran, especially after Washington on Trump's direct order assassinated top Iranian commander Lt. Gen. Soleimani in an airstrike in the Iraqi capital of Baghdad on Friday.
On Saturday, anti-war protesters rallied across the US capital as well as about 70 other US cities to denounce Trump's warmongering.
MNA/PR