"We got the news tonight that our most important partner received a slight warning assessment. But the rating for France is still very stable," Wolfgang Schäuble told the Bundestag lower house of parliament.
Schäuble warned against "dramatising" the situation but stressed: "Everyone in Europe has an interest in living up to their responsibilities and duties."
Moody's was the second of the three major ratings agency to cut France's top triple-A rating on Monday, and warned that a further downgrade could be on the cards.
Standard and Poor's did so in January but Fitch has maintained its assessment of French debt so far.
A French government spokeswoman has also sought to play down the significance of Moody's action, noting that the markets do not seem to have reacted in a negative way.
The downgrade put France behind eurozone partners such as Finland, Germany, Luxembourg and the Netherlands, which have retained top AAA ratings though they all have a negative outlook from at least one of the three agencies.
Schäuble's Berlin flat was broken into and a mobile phone stolen earlier this month, it was confirmed on Tuesday.
The 70-year-old minister was not at home at the time, but the Berliner Morgenpost newspaper said a phone was stolen. It also said that Schäuble, who has been wheelchair-bound since an assassination attempt in 1990, had declined a round-the-clock security service at his home in the southwest of the capital.