Japan's Foreign Minister has said a lack of condemnation of terror attacks by Islamic group Hamas is part of the reason her country abstained from voting for a UN resolution calling for truce in the Middle East.

Kamikawa Yoko on Saturday spoke to reporters about Japan's decision regarding Friday's vote on the resolution at the United Nations General Assembly.

The resolution calls for a "humanitarian truce" in the fighting between Israel and Hamas. It was adopted with the support of 121 member countries.

Kamikawa said the resolution contained important elements to address the humanitarian situation in the Gaza Strip, and included details Japan can agree with.

But she said Japan abstained as the resolution lacks balance as a whole due to the absence of a terror condemnation and other factors.

About Israel's expansion of its ground military activities in Gaza, Kamikawa said she keeps monitoring developments and is seriously concerned.

She said Japan will work with other countries to bring the situation under control as early as possible, and to secure an environment which will allow humanitarian activities in Gaza.

She said her country will also aggressively ask for support from relevant personnel.