"It is a solemn place; a place where we come together to honor American heroes who have made the ultimate sacrifice in service of this nation. It is not a place for politics," Harris wrote in an X post.
The vice president weighed in five days after Trump took part in a wreath-laying ceremony on Monday honoring the 13 servicemembers killed during the U.S. withdrawal from Afghanistan in 2021.
He also visited Section 60 of the Virginia cemetery, which the military considers hallowed ground. Federal law and Pentagon policies do not allow political activities in that section, but Trump's campaign posted a TikTok video with footage from the cemetery as he battles Democrat Harris in a close race for the White House.
Trump's visit drew criticism from some veterans and soldiers' relatives. The U.S. Army on Friday defended a cemetery employee who was pushed aside at Section 60, saying she acted professionally and was being unfairly attacked.
"Let me be clear: the former president disrespected sacred ground, all for the sake of a political stunt," Harris wrote.
During a speech in Pennsylvania on Friday, Trump said families of service members who died in Afghanistan had asked him to go to Arlington National Cemetery.
"I got there and we had a ceremony," Trump said. The families asked if he could come to the graves, Trump said, and then they sought a photo. "I said, 'Absolutely.' So I was taking pictures at the grave," he said.
Trump launched a concerted pushback on Saturday posting videos on his Truth Social account, showing relatives of at least seven of the 13 killed in the Afghanistan pullout defending his actions at the cemetery. Many of them addressed Harris directly and disputed her stated support for military families.
"Vice President Harris, why will you not express your condolences yourself? Why have we never heard from you?" asks Christy Shamblin, mother-in-law of Sergeant Nicole Gee, who was among those who died in the 2021 withdrawal, in one video.
Trump vice presidential pick JD Vance and press secretary Karoline Leavitt each responded to Harris' post on Saturday with one that referenced the Afghanistan pullout and accused Harris of being insensitive to the servicemembers who died there.
Trump used the third anniversary on Monday of the U.S. withdrawal from Afghanistan to try to pin the chaotic pullout under President Joe Biden on his vice president.
Harris, 59, became the Democratic nominee in the Nov. 5 presidential election after Biden, 81, pulled out of the race in July.
The vice president's response to the Trump cemetery visit may give a clue to how she would handle the topic in their Sept. 10 debate. She referred to Trump's history of insulting military veterans.
"This is nothing new from Donald Trump. This is a man who has called our fallen service members 'suckers' and 'losers' and disparaged Medal of Honor recipients," she wrote.
Trump once said the late Senator John McCain, a former Republican presidential candidate, was not a war hero even though he spent years as a prisoner of war in North Vietnam after being shot down while a Navy pilot.
Trump referred to fallen World War One veterans as "suckers" and "losers," according to his former White House chief of staff, John Kelly, a retired Marine Corps general. Trump continues to dispute that report.
It was unclear whether such incidents would sway the veterans vote. In an April report, the Pew Research Center found that military veterans favor the Republican Party.