Hey Marc Faber, don't worry about a crisis: Rogoff

Rogoff: 'Lights aren't all blinking red'

The high levels of public and private debt would only be really worrisome if interest rates were not so low, Harvard economist Ken Rogoff told CNBC on Friday.

Reacting to concerns from closely followed contrarian Marc Faber about a possible new financial crisis brewing, Rogoff said in a "Squawk Box" interview, "I don't think the lights are all blinking red yet."

Dr. Doom's big bear parade

Faber told CNBC on Thursday that he worried about a crisis developing in the second half of this year that could dwarf the downturn of 2008, because the debt-to-GDP ratios in advanced economies are higher than in 2007.

Read MoreI'm worried about a crisis bigger than 2008: Marc Faber

Downplaying the likelihood of that scenario, Rogoff acknowledged that overall debt levels are "very high." But as long as interest rates "stay benign," he doesn't see debt as a big problem.

In fact, he argued: "Credit has been flowing again and that's a good thing. It's part of the normalization."

—By CNBC's Matthew J. Belvedere.