A top economic advisor to President Donald Trump told CNBC on Monday he was "stunned" to hear Americans are feeling more optimistic about saving for retirement.

Kevin Hassett, chairman of the Council of Economic Advisers, was responding to a CNBC and Acorns Invest In You Savings Survey, which found that 57 percent of U.S. adults felt somewhat or much more confident about their ability to save for retirement than they felt three years ago.

The survey, released Monday and conducted for CNBC by SurveyMonkey in March, polled more than 2,300 adults about various aspects of financial wellness. It also found that retirement ranks as the overall top personal finance concern at 23 percent.

"I was really stunned at the numbers that so many people are feeling great about retirement," Hassett said in a "Squawk Box" interview.

He said the U.S. may be seeing "skyrocketing optimism" about retirement because "incomes are growing a lot faster" than they were. "And two, equity markets have been fantastic and a lot of people roll their retirement savings, their 401(k), into index funds."

The Trump administration has often used the stock market as barometer for its success.

Since Trump's election in November 2017, the S&P 500 has gained more than 32 percent as of Friday's close, while the Dow Jones Industrial Average has risen more than 41 percent and the Nasdaq is 48 percent higher.

Hassett, who said he pored through the survey results, said the Trump administration spends a lot of time thinking about Americans and their retirement funds. He said it's possible Trump's 2017 tax cuts could be causing people to stay in the labor market longer.

As of February, the unemployment rate was at 3.8 percent, according to the Labor Department, down from 4 percent in January. Among major worker groups, the jobless rate for Hispanics and whites has declined. Average hourly earnings have also increased.

That "could be another reason why we're seeing increased optimism," said Hassett, who previously was with the American Enterprise Institute and the Federal Reserve. "People aren't being forced into retirement because the labor market is so tight."

Disclosure: NBCUniversal and Comcast Ventures are investors in Acorns.