The Police Association says officers on the frontline are being stretched because those leaving are not being replaced at the same rate.
Official figures released to Radio New Zealand show a significant drop in the number of officers compared with last year.
The figures, released under the Official Information Act, show there were 8721 officers at the end of February this year, compared with 8940 in June 2012.
The Government has repeatedly promised there would be no cuts to frontline numbers.
Police say they had not expected so many people to leave the service recently and deny the drop is a deliberate effort to save money.
Deputy Commissioner Viv Rickard admits they did not have enough recruits coming through the Police College to replace officers leaving. He says the attrition rate was 4.1% over the past year, compared with 3% over the past three years.
"We budgeted at around three-and-a-half (percent), the attrition's higher, so we didn't have so many people coming through the college."
However, Mr Rickard denies it is a money-saving measure and police will make the numbers up over the next few intakes.
The Police Association says, in the meantime, the same amount of work is being done by fewer people.
President Greg O'Connor says the tendency is to hold vacancies over for longer to take the pressure off the budget. "The people that suffer then are the public."
Mr O'Connor says it is vital that the 200 officers are replaced as quickly as possible, as the attrition rate will continue to rise while officers are asked to do more with less.