"We are monitoring the situation closely," she said, without offering further details.
Greece is in arrears to the IMF, having failed to pay a 1.5 billion-euro ($1.7 billion) loan due last Tuesday. The IMF said it couldn't get involved in a further bailout of Greece if the country remained in arrears.
The IMF last week also said that Greece would need debt relief as well as new financing worth more than 60 billion euros through 2018 to avoid financial collapse.