He said speculation New Zealand would reduce its representation at the United Nations was wrong.
"There is no way in the world that is going to happen and nor have I seen any proposal for it to happen."
That took account of New Zealand's bid for a seat on the Security Council in 2015 "but it also takes account of the fact that this is an important part of New Zealand's international face and we believe in doing it properly".
He also said that any proposal to outsource consular services would be controversial "and you can take it that minister would be extremely sensitive about that".
Foreign Affairs chief executive John Allen and the senior leadership team have responded to the Government's requirement to cut costs by proposing cutbacks primarily focused on administrative staff posted overseas from Wellington.
They cost on average about $500,000 a year, including salaries, allowances, schooling for children and travel.
The ministry employs about 900 and staff will be consulted about the proposals.
Some property is expected to be sold.
Not many missions are expected to be shut - though Stockholm, which was opened in 2008, and Warsaw, which was opened in 2005, are thought to be marked for closure.
The Government has asked all departments to make savings and Mr McCully said his ministry had undergone relatively little change in the past.
"Every other ministry in the New Zealand public service has had significantly more change imposed on it by governments over the past 25 years and in that sense the Ministry of Foreign Affairs has a bit of catching up to do."
He said that Mr Allen and his team hadnot been asked to come up with a savings target.