Christine Lagarde, head of the International Monetary Fund. Thomson Reuters

Bitcoin is too expensive for one of the most powerful women in finance. 

Christine Lagarde, the head of the International Monetary Fund, on Friday told CNBC's Sara Eisen that bitcoin is "too expensive for me at the moment" when asked if she would ever buy into the red-hot digital currency. 

Lagarde last month gave a soft defense of the cryptocurrency during a speech in London.  She said cryptocurrencies such as bitcoin could "give existing currencies and monetary policy a run for their money." The IMF is one of the largest supranational organizations and facilitates cooperation between nations on monetary and fiscal policy. 

"Not so long ago, some experts argued that personal computers would never be adopted, and that tablets would only be used as expensive coffee trays," she said. "So I think it may not be wise to dismiss virtual currencies."

During the wide-ranging interview with Eisen, Lagarde shared her thoughts on the bitcoin crackdown in China. She said the ban on initial coin offerings, a cryptocurrency-based fundraising method, in China was "done on that on the basis of the analysis that it was at least strongly dominated by...speculation and Ponzi-like schemes, which is certainly showing that they are paying attention."

ICOs allow startups to raise money by issuing their own cryptocurrencies. They've come under scrutiny by regulators because companies can use them to raise quick money without having to disclose substantive information to investors. The Securities and Exchange Commission charged one man with operating two fraudulent ICOs last month. 

Still, despite the bad actors Lagarde thinks people should pay attention to the market.

"When I look at my own country where, you know, all transactions between ... my compatriots and the treasury department is all now on digital support," she said. "I think there are massive changes taking place at the moment which everybody needs to be attentive to."

Get the latest Bitcoin price here.