Treasury Secretary Steven Mnuchin on Thursday sought to quell concerns about lower tax refunds this tax season, offering new data showing a recent surge in refunds.

"People have been very focused on tax refunds," Mnuchin told CNBC's Hadley Gamble. "Tax refunds are up 17 percent week over week. That basically gets us to the same level as last year."

He didn't give a dollar amount, and the Treasury Department did not immediately respond to a CNBC query.

The tax filing season kicked off at the end of January and there has been grumbling about lower refunds, even though many consumers saw a tax break last year with the new bill. Through Feb. 15, the average refund check was down 16 percent from last year, according to the IRS.

"I would emphasize that even if people had perfectly done their withholding — withholding is complicated and I encourage people to go to the withholding calculator — people really should be focused on the fact they're paying lower taxes," Mnuchin said. "Those lower taxes is money going back into the economy, and that's why we have the economic growth we do."