Merkel : "Victoria Nuland statement unacceptable" |
A recording of the exchange was posted online, with the US hinting at Russia's involvement in bugging and leaking it.
The EU and US are involved in talks to end months of unrest in Ukraine.
In Kiev, Ms Nuland - an assistant secretary of state - said she would not make a public statement on the matter.
The state department said she had apologized in private to EU officials.
Note EU-Digest: diplomats like Ms Victoria Nuland .who can't control what they say should not be working in the Diplomatic Service of their countries. .
Read more: BBC News - Victoria Nuland gaffe: Angela Merkel condemns EU insult