The Kiwi dollar dipped against the United States currency following weak Chinese data.
Escalating tension between Saudi Arabia and Iran after the execution of a prominent Shiite cleric is also increasing demand for the greenback, a safe haven currency.
The New Zealand and Australian dollars sagged amid concern that China's economy remains anemic after a fifth month of contraction in factory activity.
Australia's dollar slid to 72.38 US cents, down 0.7 percent from December 31, while New Zealand's currency was 0.9 percent weaker since then at 67.71 US cents.
Japan's currency held its biggest monthly gain versus the dollar since January 2014 after Saudi Arabia cut diplomatic ties with Iran following an attack by protesters on its embassy in Tehran.