Suzuki said that Japan is monitoring developments in the currency market with a sense of urgency.
Japan intervened in the currency market in September to stem the yen's rapid fall and the market has been alert for possible further action.
Suzuki said there was no change in our stance that we will take an appropriate response, and that excessive volatility caused by speculative moves is unacceptable.
Japan spent 2.84 trillion yen $19 billion buying the yen for dollars last month, likely in a single day on Sept. 22, its first such intervention since 1998. The action took some selling pressure off the yen, but the widening monetary policy divergence between Japan and the United States has weakened the Japanese currency.
Japanese authorities may have been involved in stealth intervention in the past few days, according to speculation.
Suzuki didn't say whether that had happened.
He said that there is a time when we say in public intervention that we don't, while at another time we don't.