But the move only comes after the family of slain soldier Sgt Dillon Baldridge revealed to The Washington Post that President Trump had made the offer in a phone call.
Mr Baldridge said the President called him in the weeks following his son's death in Afghanistan in June.
In the call, Mr Baldridge vented his frustration at the US military survivor benefits program.
President Trump then offered to send the family a cheque for US$25,000, from his own account.
“He said, ‘I’m going to write you a check out of my personal account for $25,000,’ and I was just floored,” Mr Baldridge said.
“I could not believe he was saying that, and I wish I had it recorded because the man did say this.
He said, ‘No other president has ever done something like this,’ but he said, ‘I’m going to do it.’ ”
The White House now says the cheque has been sent, although it accused the media of using the President's "generous and sincere" for it's own "agenda".
"The cheque has been sent," White House spokeswoman Lindsay Walter said.
"It’s disgusting that the media is taking something that should be recognised as a generous and sincere gesture, made privately by the President, and using it to advance the media’s biased agenda.”
A White House official said the payment "has been in the pipeline since the President's initial call with the father".
"There is a substantial process that can involve multiple agencies anytime the President interacts with the public, especially when transmitting personal funds", the official said.
"The President has personally followed up several times to ensure that the cheque was being sent. As stated earlier, the cheque has been sent."
The slain soldier's step-mother, Jessica Baldridge, made light of the furore.
"We just thought he was saying something nice," she told local North Carolina television station WTVD.
"We got a condolence letter from him and there was no cheque, and we kind of joked about it."
It's another controversy surrounding President Trump's handling of gold star families.
Earlier this week, the President accused his predecessors of never, or very rarely, calling families of slain soldiers, when in fact, they often did.
And Democratic congresswoman Frederica Wilson accused President Trump of saying to a soldier's widow that her husband “knew what he was signing up for, but I guess it hurts anyway.”
Ms Wilson was travelling with Myeshia Johnson, whose husband Sgt La David Johnson, was killed in Niger.
Ms Wilson says she heard Mr Trump's comment on speakerphone.
The President denied the comments in a tweet, while White House press secretary Sarah Huckabee Sanders said President Trump was "completely respectful" during the call.
