Gears are often a source of noise, but this can be reduced. Firstly, are the gears matched such that they mesh correctly? Is the backlash between the gears set?
Secondly (I'm assuming these are spur gears), are they straight cut? A lot of noise can be minimised by replacing these with helical cut gears, though you'll then have to consider shaft thrust.
Thirdly, what are the gears made of, and are they sufficiently lubricated?
Finally, how are the gears enclosed? Dealing with engines, complaints of "noisy gear train" are often a result of the gear train cover being a large, resonant panel. Sure, it sounds and looks like gear train noise, but isolating that panel can reduce the noise by huge amounts. Possibly not relevant to your application, but it's worth thinking about.
It's impossible to say whether the use of roller or friction drive will reduce noise without seeing your specific application.