The French bank's chief executive is to be probed over a communique sent by the bank which was concerned with the impact of the collapse US sub-prime mortgage market.
The statement said that that BNP Paribas had suspended withdrawals on three funds worth a total of $2.16 billion, which subsequently prompted a fall in the stock market.
In an interview with French radio station RTL, Ms Lagarde said that she intended to quiz BNP Paribas chief executive Baudouin Prot over the matter.
She said: "Of course, I will ask Mr Prot for explanations as to how they managed that moment.
"I think they are looking again at how they communicate and manage this type of question."
Ms Lagarde did not however specify when she would be speaking to Mr Prot.