Japanese authorities appeared unhappy to sit back and watch the yen fall to a new low since November at the start of the Asian session.
Japan's top currency diplomat, Masato Kanda, said that speculative movements could be seen in the market and warned that Tokyo was ready to act if necessary.
He said, if this move continues, the government will deal with it accordingly without rejecting any option.
It was the strongest warning issued by Japanese authorities in weeks, raising the possibility of government intervention if the downturn continues.
Kanda, also Japan's vice finance minister for international affairs has played a key role in the country's efforts to stem the yen's sharp fall last year.
Japan intervened in currency markets last year in September when the US dollar rose past 145 yen, prompting authorities to buy yen to save the currency.
The yen is currently trading weak at around 147.45 against the greenback, having touched a new 10-month low of 147.81.
