U.S. sanctions have prevented the Iranian Red Crescent from obtaining any foreign financial aid to assist victims of flooding that has killed at least 70 people and inundated some 1,900 communities, the group said on Sunday.
U.S. Secretary of State Mike Pompeo said last week that Washington was ready to help via the Red Cross and Red Crescent, but accused Iran's clerical establishment of "mismanagement in urban planning and in emergency preparedness".
"No foreign cash help has been given to the Iranian Red Crescent society. With attention to the inhuman American sanctions, there is no way to send this cash assistance," the Red Crescent said in a statement.
It said the group had received some non-financial help from abroad which had been distributed to flood victims.
Iranian Foreign Minister Mohammad Javad Zarif said last week that U.S. sanctions - reimposed after Washington quit a 2015 nuclear deal between Iran and six world powers - were impeding aid efforts to flood-stricken towns and villages.
"Blocked equipment includes relief choppers: This isn't just economic warfare; it's economic TERRORISM," he said on Twitter.
The flood disaster, arising from exceptionally heavy rainfall since March 19, has left aid agencies struggling to cope and seen 86,000 people moved to emergency shelters.
The government has told citizens, and especially flood-affected farmers, that all losses will be compensated.