Donald Trump has been widely condemned after suggesting disinfectant could be injected into patients as a possible treatment for Covid-19.
The president noted that researchers were looking at the effects of disinfectants on coronavirus and wondered aloud if they could be injected into people, saying the virus "does a tremendous number on the lungs, so it would be interesting to check that".
But William Bryan of the Department of Homeland Security science and technology unit said health officials were not considering such treatment.
The White House was also pitching "emerging" research on the benefits of sunlight and humidity in diminishing the threat of coronavirus.
Past studies have not found good evidence that the warmer temperatures and higher humidity of spring and summer will help tamp down the spread of the virus.
But Mr Trump said at a White House briefing that there are "emerging results" from new research that suggest solar light has a powerful effect in killing the virus on surfaces and in the air. He said scientists have seen a similar effect from higher temperatures and humidity.
A biocontainment lab in Maryland has been conducting testing on the virus since February, Mr Bryan said.
"The virus is dying at a much more rapid pace just from exposure to higher temperatures and just from exposure to humidity," he said.
Mr Bryan added that having more knowledge about this could help governors make decisions about how and when to open their state economies, a key policy for the president.
However, the DHS expert stressed that emerging results of the light and heat studies do not replace social distancing recommendations.
Mr Trump, who has consistently looked for hopeful news about containing the virus, was asked if it was dangerous to make people think they would be safe by going outside in the heat, considering so many people have died in Florida.
"I hope people enjoy the sun. And if it has an impact, that's great," he replied, adding: "It's just a suggestion from a brilliant lab by a very, very smart, perhaps brilliant man.
"I'm here to present ideas, because we want ideas to get rid of this thing. And if heat is good, and if sunlight is good, that's a great thing as far as I'm concerned."
The president has often talked up prospects for new therapies and offered rosy timelines for the development of a vaccine.
Earlier in the month, scientific advisers told the White House there was no good evidence that the heat and humidity of summer will rein in the virus without continued public health measures.
Researchers convened by the National Academies of Sciences, Engineering and Medicine analysed studies done so far to test virus survival under different laboratory conditions as well as tracking where and how Covid-19 has spread so far.
"Given that countries currently in 'summer' climates, such as Australia and Iran, are experiencing rapid virus spread, a decrease in cases with increases in humidity and temperature elsewhere should not be assumed," the researchers wrote in response to questions from the White House Office of Science and Technology.
They noted that during 10 previous flu pandemics, regardless of what season they started, all had a peak second wave about six months after the virus emerged.