TEHRAN (Reuters) - The latest sanctions against Iran are pathetic, President Mahmoud Ahmadinejad said on Saturday, warning world powers they would regret their bullying.

EDITORS' NOTE: Reuters and other foreign media are subject to Iranian restrictions on leaving the office to report, film or take pictures in Tehran. Iranian President Mahmoud Ahmadinejad speaks during an anti-chemical weapon ceremony in Tehran June 29, 2010. REUTERS/Morteza Nikoubazl

In his first speech since U.S. President Barack Obama signed into law sanctions targeting Iran’s vulnerable fuel imports, Ahmadinejad said the measures would not hurt the economy or stop Iran taking a greater role in world affairs.

“They know that there is a sleeping lion in Iran which is waking up and if she wakes up all the relationships in the world will change,” he told industrialists. “Their pathetic acts show they know what a great human power is hidden in Iran.”

The U.S. law followed sanctions agreed by the U.N. Security Council and the European Union, all aimed at pressuring Tehran to curb a nuclear program some countries fear is aimed at making a bomb -- something Iran denies.

“They thought that by having meetings and talking to each other and signing papers they could stop a great nation’s progress,” Ahmadinejad said.

“Iran is much greater than what they can perceive it in their small minds,” he added. “We know that if this Iranian civilization awakes then there would be no more room for arrogant, corrupt and bullying powers.”

The hardline Iranian leader has consistently played down the impact of sanctions. He called the U.N. resolution a “used handkerchief” and said that Iran could become self-sufficient in gasoline within one week if needed -- more likely a rhetorical flourish than a realistic assessment of its energy needs.

Last week, France’s Total joined a list of oil companies that do not sell gasoline to Iran which, despite being the world’s fifth-largest oil producer, lacks sufficient refining capacity and imports up to 40 percent of its petrol.

Two days ago, South Korea’s GS Engineering & Construction called off a $1.2 billion contract to sweeten gas from the South Pars field. This one of the world’s biggest gas fields, but Iran has yet to exploit it fully, partly because sanctions have limited foreign investment and knowhow.

Ahmadinejad has said he is prepared to return to talks with major powers on the nuclear question, but on certain conditions only, and not before the end of August -- a delay he said was intended to “punish” the West.

EU foreign affairs chief Catherine Ashton, with the backing of the major powers that have been involved in nuclear talks with Iran in the past, wrote to Tehran’s chief nuclear negotiator last month inviting him to resume negotiations.