The Greens want the Government to put more pressure on Washington as tensions escalate in Gaza.
Foreign Minister Murray McCully says America's highest priority must be to re-engage Palestinians and Israelis in peace talks.
But Green MP Kennedy Graham says so far that's failed, and US rhetoric is sympathetic to Israel.
"Both sides are wrong, but Israel has engaged – and not for the first time – excessive use of force and New Zealand needs to be seen to be condemning that," says Dr Graham, "and I would hope the United States would too."
Eleven Palestinian civilians have been killed in an Israeli air strike on a house in Gaza, the highest civilian death toll in a single incident during five days of fighting.