"The West is waging a war against the Iranian economy," he said.
Iran's central bank has provided enough hard currency to finance imports into the country, despite Western economic sanctions designed to cut its oil earnings, he said.
Ahmadinejad said the country's enemies were waging a "psychological war" against it, adding: "Enemies have managed to reduce our oil sales but hopefully we will compensate for this."
The Iranian rial has plunged to a record low against the US dollar earlier Tuesday, following a recent series of exchange tumbles.
The Iranian rial has depreciated 57% in the past three months.
Meanwhile, Iranian lawmakers have signed a petition to summon Ahmadinejad to parliament for questioning over the rapid drop in the value of the country's currency.
A lawmaker, Mohammad Bayatian, said enough signatures have been collected to bring Ahmadinejad before the 290-seat chamber for the second time. His comments were posted Tuesday on the parliament's website.
Ahmadinejad defended his economic record on Tuesday, saying a phase-out of food and fuel subsidies that he launched in 2010, which has boosted the official inflation rate to around 25 percent, had been successful.