Total last week said it would pay $245 million to the U.S. Justice Department and $153 million to the Securities and Exchange Commission to put "an end to an investigation initiated in 2003 concerning petroleum contracts awarded in Iran in the 1990s."
De Margerie said he was barred from commenting on the U.S. case but said similar investigations in France were without merit.
"What we did wasn't illegal according to French law," he was quoted by Bloomberg News as saying. "We didn't pay bribes, we didn't pay Iranian authorities. Our contracts weren't illegal."
Parisian authorities said last week de Margerie and others tied to the contract could face corruption charges for the Iranian activity.
Sanctions on Iran's energy sector are meant to starve it of financing for a controversial nuclear program, which Iran says is for peaceful purposes.
Italian energy company Eni said in April it was the target of a similar U.S. investigation regarding its work in Iran.