The long-term personal lawyer of $130,000 (£95,000) in 2016, in a statement to the New York Times.
It follows US media reports that the actress known as Stormy Daniels was paid to sign an agreement stopping her discussing an alleged affair.
She first said she had a relationship with Mr Trump in a 2011 interview.
The lawyer has previously said Mr Trump “vehemently denies” it occurred.
“Neither the Trump Organization nor the Trump campaign was a party to the transaction with Ms. Clifford [Stephanie Gregory Clifford, her real name], and neither reimbursed me for the payment, either directly or indirectly,” Michael D. Cohen said in a statement to The New York Times.
He said he told the Federal Election Commission the same after a watchdog group filed a complaint about the payment serving as an “in-kind” political contribution to Mr Trump’s campaign.
“The payment to Ms. Clifford was lawful, and was not a campaign contribution or a campaign expenditure by anyone,” Mr Cohen said.
In a 2011 interview with InTouch magazine, the actress said she began a sexual relationship with Mr Trump in 2006, shortly after Melania Trump gave birth to his son Barron.
The reports re-emerged in January when the Wall Street Journal reported that she was paid to sign a non-disclosure agreement in the run up to the 2016 election.
Ms Clifford was believed to be in discussion with US media about an appearance to discuss Mr Trump at the time, the report said.
The New York Times newspaper said Mr Cohen declined to answer questions on why the payment was made, and if Mr Trump knew about it.
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In January, Stormy Daniels released a statement denying having an affair with Mr Trump.
She has since made public and television appearances where she has refused to directly answer questions about it.