The assertion comes in the wake of recent allegations, mainly from Republican Party, that the foundation received foreign funding while his wife Hillary Clinton was a Senator and the Secretary of State.
The allegations include that the Clinton Foundation received money from Indian politician Amar Singh when Hillary was the New York Senator when the Senate discussed and passed the landmark India-US Civil Nuclear Bill in 2008.
"There is no doubt in my mind that we have never done anything knowingly inappropriate in terms of taking money to influence any kind of American government policy," Clinton told the NBC's Today's Show in an interview.
The allegations are not new, but have surfaced afresh, courtesy the Republican Party, after Hillary Clinton announced her second presidential bid last month.
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A book on these allegations is scheduled to be released tomorrow.
According to excerpts released by the publisher, the author of the book "Clinton's Cash" alleges that donations made by Indian politicians influenced Clinton's voting during the nuclear deal.
Clinton, who was also the co-Chair of the Senate India Caucus, had voted in favour of the bill.
"'Clinton's Cash' is attempting to rewrite history to fit a pre-determined partisan narrative. It only takes a quick look at Hillary's actual voting record and statements to see that this conspiracy theory doesn't even come close to passing the smell test," Josh Schwerin, spokesperson of the Hillary's presidential campaign, told PTI.
Separately, Singh had also denied any wrongdoing and had claimed he was a victim of "assumptions and rumour-mongering.