Speaking at a press briefing on Monday, Kayleigh McEnany said: "I think the world is looking at us as a leader in Covid-19.”
Her remarks come just days after the US reported the highest ever number of new daily cases in the world.
The total number of infections is approaching three million, while 130,000 deaths have been recorded.
Responding to a question from the media about Donald Trump's claims about low mortality rates from Covid-19, Ms McEnany said the claims were "rooted in science".
Ms McEnany said the low mortality rates were due to "extraordinary work on therapeutics" and having adequate PPE and ventilators.
"The president was noting the fact that the vast majority of Americans who contract coronavirus will come out on the other side of this," she said.
"Of course he takes this very seriously. Of course no one wants to see anyone in this country contract Covid, which is why the administration has fought hard to make sure that's not the case with our historic response effort."
Ms McEnany said the low mortality rates were due to the "extraordinary work on therapeutics" and having adequate PPE and ventilators.
She added: "We grieve when just one life is lost, but he (Mr Trump) wants to note the progress that we've made in treating this very serious virus...he's pulled down bureaucracy and allowed us to get to a place where we can have this declining mortality rate."
A surge in cases over the last week has put Mr Trump's handling of the crisis under the microscope and led several governors to halt plans to reopen their states after strict lockdowns.
On travel restrictions, Ms McEnany said: "President Trump and the administration have taken bold, decisive and frequent action to secure our homeland and a big part of that has been the travel restrictions and we're working with countries around the world.
"We hope to have a day where international travel is open, but right now this is about putting America first."
On conflicting messages about wearing a mask, Ms McEnany said the president was "clear" that he would wear a mask in a confined space where social distancing was not possible.
Three of the top US medical organisations issued an open letter urging Americans to wear masks, social distance and wash hands often to help stop "the worst public health crisis in generations".
The American Medical Association, American Nurses Association and American Hospital Association issued the plea in the absence of a mask-wearing order from Washington and said steps taken early on that helped slow the spread of Covid-19 "were too quickly abandoned."
The White House again rejected calls for a nationwide order to wear face coverings, with White House chief of staff Mark Meadows saying on Fox News that it is a matter for governors and mayors to decide.
In New York, Governor Andrew Cuomo said he was concerned about reports of large gatherings over the holiday weekend in New York City, on Fire Island and other places.
"I understand people are fatigued," he said. "We've been doing this for 128 days. I get it. But it doesn't change the facts, and we have to stay smart."