Trump also defended his energy and health and disclosed that he had a CT scan, not an MRI scan, during an October examination about which he and the White House delayed offering details.
Trump said in the interview he regretted undergoing the advanced imaging on his heart and abdomen during an October visit to Walter Reed National Military Medical Center because it raised public questions about his health.
His physician said in a memo the White House released in December that he had "advanced imaging" as a preventative screening for men his age.
Trump had initially described it as an MRI but said he did not know what part of his body he had scanned.
A CT scan is a quicker form of diagnostic imaging than an MRI but offers less detail about differences in tissue.
The president's doctor, Navy Captain Sean Barbabella, said in a statement released on Thursday by the White House that Trump underwent the exam in October because he planned to be at Walter Reed to meet people working there.
Trump had already undergone an annual physical in April.
"President Trump agreed to meet with the staff and soldiers at Walter Reed Medical Hospital in October. In order to make the most of the president's time at the hospital, we recommended he undergo another routine physical evaluation to ensure continued optimal health," Barbabella said.
Barbabella said that he asked the president to undergo either a CT scan or MRI "to definitively rule out any cardiovascular issues" and the results were "perfectly normal and revealed absolutely no abnormalities".
White House press secretary Karoline Leavitt said in a statement that the president's doctors and the White House have "always maintained the president received advanced imaging" but said that "additional details on the imaging have been disclosed by the president himself" because he "has nothing to hide".
"In retrospect, it's too bad I took it because it gave them a little ammunition," Trump told The Wall Street Journal.
"I would have been a lot better off if they didn't, because the fact that I took it said, 'Oh gee, is something wrong?' Well, nothing's wrong."
Trump said the practice of taking aspirin has made him more prone to bruising, injuries he has at times tried to conceal cosmetically and which have prompted questions about his health.
"I'm a little superstitious," the 79-year-old said.
"They say aspirin is good for thinning out the blood, and I don't want thick blood pouring through my heart," Trump told the newspaper.
"I want nice, thin blood pouring through my heart. Does that make sense?"
Trump, who said he is in "perfect" health, also dismissed accusations that he had fallen asleep during recent White House meetings. Videos appeared to show him struggling to stay alert.
"Sometimes they'll take a picture of me blinking, blinking, and they'll catch me with the blink," Trump said.
with AP
