The president’s statement came less than an hour after organizers announced the debate would take place virtually.
The Commission on Presidential Debates said the decision had been taken to “protect the health and safety of all those involved”, with the President’s positive opinion coronavirus test having come just days after the first debate last week.
The committee said the two candidates would appear in the second televised debate, scheduled for next Thursday, from different locations.
But, in an interview shortly after the announcement, Mr. Trump said, “I’m not going to have a virtual debate.”
He told Fox Business that the arrangement was “not acceptable to us”.
Mr. Trump returned to the White House Oval Office on Wednesday, although he is still recovering from COVID-19.
His doctors said the president had not shown any symptoms of coronavirus in the past 24 hours.
In a video posted to his Twitter account later Wednesday, Mr. Trump promised that the treatment he received in a military hospital would be free for Americans.