Asked to answer a question with a "bit of French please", he told the reporter: "Not today. I got to refresh myself on that."
The response raised eyebrows among Francophiles, mainly because Kerry is known to speak French and attended Swiss boarding school a a child, BBC News reported.
The question was also asked in French.
Kerry spoke after meeting Canadian Foreign Minister John Baird at the State Department -- the first foreign leader to be welcomed by Kerry since he took up office as the secretary of state late last week, according to Agence France-Presse.
Baird, to his credit, offered an answer to the question in both English and French, Politico reported.
During his 2004 presidential bid, Kerry was attacked for his ties to France at a time when US-France relations had soured due to the war in Iraq.
Since then, he's appeared to downplay his French connections, which also included spending summers at his mother's family estate in Brittany, according to AFP.