"We're going to still see elements of the disease increasing in other parts of the world and until we have adequate testing, rapid testing, it's very hard to see how we're going to reboot in the next 30 days," Fink said on CNBC's "Squawk Box."
Fink expressed confidence that the U.S. will make progress on Covid-19 treatments, minimizing the severity of the disease. "Through that process, I do believe we'll be able to reboot. I do believe we're going to have a better, more normalized environment," he said.
"But it may not be in June or July. It may be in August."
Fink, whose firm is the world's biggest asset manager, said businesses will be "very cautious" and "protective of their employees" as they consider when and how to relax work-from-home policies.
"They want to make sure their employees feel good about coming back to the office," he said. "Let's be clear: Anxiety is still very high."
"Regular testing on a global scale, across all industries, would both help keep people safe and help get the economy back up and running," Bezos wrote. "For this to work, we as a society would need vastly more testing capacity than is currently available."
There are signs that daily increases in new Covid-19 cases in the U.S. may be slowing, causing the national debate to begin focusing on how the U.S. will reopen the economy.
President Donald Trump recently announced a new group — made up of business leaders from all manner of industries — aimed at focusing on how to reboot business. Trump, who has said he thinks some states may be able to relax restrictions by the end of April, had a call with many of those executives Wednesday.
Fink said he of course wants the U.S. to "have the ability to reboot," but he repeated his current concerns about testing. "I know many leaders told the president yesterday, we need to have adequate to make sure we have a secured environment."
CNBC requested comment from the White House on Fink's comments and was referred to an interview given Thursday morning by press secretary Kayleigh McEnany on Fox News.
McEnany said it was "misreported" that business leaders "forcefully" told Trump that more testing is needed before the economy can be restarted. "In fact they said testing is important, something the president acknowledges and has done," McEnany told Fox News.
"We're in a strong place and I can assure you that the guidance being put out today is in line with what the experts are saying, it's in line with what the data is showing," she said. "It's a plan to put this economy back on track ... to the hottest in modern history, that President Trump created, and also protect American lives and we have the perfect president to do that."
In Thursday's interview, Fink also said the stock market's low last month may have been the bottom of the panic stemming from the coronavirus.
"If the disease curve in the developed world continues to decline [and] at the same time we see the curve from governmental support for monetary policy and fiscal policy worldwide increases, we could have seen the bottom," said the BlackRock chairman and CEO.