The Iranian president made the assertions in a speech on Monday addressing the problems caused by low rainfall trends, which experts say is threatening Iran's agriculture.
"Today our country is moving towards drought, which is partly unintentional due to industry and partly intentional, as a result of the enemy destroying the clouds moving towards our country and this is a war that Iran is going to overcome," Mr Ahmadinejad said in a speech in the Caspian Sea city of Gonbad-e Kavus to mark its registration as a Unesco World Heritage site.
Although Iran is recognised as having one of the world's driest climates, the comments were the latest in a series of allegations by officials of a Western conspiracy to turn its water shortage into a major crisis.
In July, Hassan Mousavi, head of Iran's cultural heritage organisation and one of Mr Ahmadinejad's vice-presidents, urged meteorological experts to investigate the possibility that the west was engineering a draught in southern Iran, traditionally one of the country's most parched regions.
"I feel that the world arrogance and colonisation (Iranian official code language for the US and its allies) by using their technologies, are affecting the environmental situation in Iran," he said.
Specialists have recently warned that low rainfall has reached "undesirable levels", producing officially-designated draught conditions in more than three-quarters of the country.
Previously, Mr Ahmadinejad has accused European nations of deliberately emptying clouds to produce torrential storms in their own countries that would lead in turn to rain shortages in the Middle East. He said Iran would pursue the matter through international legal channels.
Earlier this year, the Iranian leader accused Western states of creating the HIV to weaken the developing world and create a market for pharmaceuticals.
source The Telegraph