Mr Trump appointed the billionaire investor on Wednesday as an adviser on regulatory reform.
When questioned by CNBC if his stake in an oil refinery firm would affect his stance on environmental regulations, Mr Icahn played down the potential clash.
He added that he would not be in the Cabinet and so "not making any policy".
Mr Icahn is a large investor in oil firm CVR Energy, along with other US businesses including PayPal and insurance firm AIG.
Asked if that would shape his advice, he said it was "almost a crazy issue", and gave the example of senior bank executives advising the Trump team on banking regulation.
Instead, he said, the "major issue" was that excessive regulation has hurt American businesses.
He added that environmental and banking regulations had become particular obstacles to investment.
Carl Icahn has denied his extensive business interests could pose a conflict of interest when advising President-elect Donald Trump.