While some banks had passed on recent OCR reductions it was "fair to say we have been disappointed with the response to date," Deputy Governor Grant Spencer said at the release of the latest Financial Stability Report in Wellington.
He defended monetary policy as a means to lift the economy out of its first recession in a decade and said it wasn't "reasonable to say the OCR has lost its punch."
The central bank embarked on its steepest easing of monetary policy last year, and has slashed 575 basis points from the benchmark rate since July. Last month it cut the OCR to a record-low 2.5%.
Floating interest rates at the major banks averaged 6.45% in May, down from 8.2% in December and six-month fixed rates have dropped 149 basis points to 5.5% in the same period.
In contrast, five-year fixed rates have only fallen to 7.5% from 7.85%, according to the Good Returns website.
Spencer said there was still "potential scope" for future cuts to the OCR, but the central bank wasn't "considering changing our policy approach or introducing unconventional measures."
The Reserve Bank will issue the next monetary policy statement on June 11.
