A lot of noise is produced when you whistle.
It's important that you try and minimise the amount reaching the microphone by whistling across the business end of the mic, rather than straight into it.
Also make sure you top & tail each ciip and bounce to clip before invoking V-Vocal.
If your whistle is quite high in pitch, try shifting it down an octave, and again, bounce it before applying VV.
Take a safety copy of the original before you start any of this.