TRX 300 weird vibration

Hi,
I’m new to the forum and this is my first post so here goes.

I have a Trx 300 Awd, and there is a weird vibration and noise appeared ill try to explain it best I can, sitting on the bike with both feet on the pegs as I squeeze the throttle gently at very minimal rev’s I can hear a vibration down to my left foot and I can feel it through my left foot vibrating through the peg.

so far so good, it certainly from that side of the bike and it only lasts or seems to happen at a certain rev point as it passes when I apply more throttle. This is the case when in neutral and driving in gear, would I be right in saying that the drive to the rear wheels is down that side could it be something to do with that.

Any thoughts ideas would be great, Would it still be ok to use to use or should I get to the bottom of this first?

thanks

scott