President Trump said he understands why former first lady Barbara Bush, who died last April, leveled harsh criticism of him in a newly published biography after he openly mocked her sons during his 2016 presidential campaign.

“I have heard that she was nasty to me, but she should be. Look what I did to her sons,” Trump told the Washington Times in an exclusive Oval Office interview.

“I have heard that she was nasty to me, but she should be. Look what I did to her sons.” — President Trump

Trump’s comments were in response to Bush’s characterization of him in the biography “The Matriarch: Barbara Bush and the Making of a Dynasty.” Bush called Trump a "symbol of greed," according to the book's author, Susan Page.

TRUMP 'NOT MENTALLY WELL,' SHOULD BE REMOVED UNDER 25TH AMENDMENT, FORMER BUSH ETHICS ATTORNEY SAYS

Bush’s dislike of Trump goes back at least to the 1990s, according to her diary, after he criticized her husband, the late former President George H.W. Bush, during a charity benefit, the Times reported. (The former president died in November.)

“Trump now means greed, selfishness and ugly. So sad,” she wrote in her diary at the time.

“Trump now means greed, selfishness and ugly. So sad.” — Barbara Bush, in her diary

Her views of the real estate mogul became more pronounced after Trump publicly mocked two of her sons -- former President George W. Bush for his decision to invade Iraq, and former Florida Gov. Jeb Bush, who ran against Trump in the 2016 Republican primaries. Trump famously slapped the description "low energy" on Jeb Bush.

GEORGE AND BARBARA BUSH THROUGH THE YEARS

“Look, she’s the mother of somebody that I competed against,” Trump said. “Most people thought he [Jeb Bush] was going to win and he was quickly out.”

Jeb Bush dropped out of the race after a disappointing showing in South Carolina.

“I hit him very hard in South Carolina,” Trump told the paper. “Remember? He was supposed to win South Carolina and I won it in a landslide. I hit him so hard.

“Remember? [Jeb Bush] was supposed to win South Carolina and I won it in a landslide. I hit him so hard. — President Trump

Bush also reportedly blamed Trump for her worsening health.

“Barbara Bush blamed Donald Trump for her heart attack," Page wrote, according to the Hill.

CLICK HERE TO GET THE FOX NEWS APP

"It wasn't technically a heart attack, though she called it that,” the book says. “It was a crisis in her long battle with congestive heart failure and chronic pulmonary disease that hit her like a sledgehammer one day in June 2016" when Trump secured the Republican nomination.

The day after the 2016 presidential election, Bush “discovered to my horror that Trump had won,” according to the book.