"He is giving this thing his best shot and we should support him very strongly in that."
Any offer of help would be contingent on Mr Kerry making some progress and the pair had agreed that the window for a two-state solution was closing - 18 months to two years.
"The settlement process [by Israel] in the West Bank is closing down the room for manoeuvre," Mr McCully said.
"As they say, the facts on the ground are making it increasingly difficult."
Mr Kerry had run through some of the ways in which New Zealand could support the process, including capacity building for Palestine.
Asked if it could mean being part of an international force maintaining a buffer zone between Israel and Palestine, Mr McCully said "we would certainly look very positively at any requests for support in that regard".
He pointed to New Zealand's presence in the Sinai for 31 years keeping the peace between Israel and Egypt.
While the focus was on the Middle East, Mr McCully was reassured by Mr Kerry and in his talks with other senior officials that the Pacific and parts of the Asia Pacific were strongly in the mind of the US.
At a speech earlier in the day Mr McCully said formal relations between the US and New Zealand were excellent.
"We have found a new normal."
Mr Kerry made an unscripted statement during a photo opportunity but took no questions.
"Our friends in New Zealand are just that, a special relationship, 175 years of an active relationship. We're going to build on the Wellington and Washington Declarations.
"But New Zealand has been a partner in a lot of our initiatives and interests, and particularly helping out in a place like Afghanistan ...
"The regional issues, particularly on the Korean Peninsula and the challenges in the South China Sea, are important to all of us. And we rely on our friends in New Zealand for the strength of a relationship not just in the region but globally. We share a lot of values and a lot of interests."
