if they have a glased impervious upper surface …. lift the soiled tile , take outside and hose it down , wipe dry and replace.
if textured , not smooth on top surface …. i'd wipe with a piece of absorbant paper towel, them give a spray with diluted F10SC …. (1:200 in water) , wait 30min to air dry …. done , return to tank.
note that tiles are designed to a very have porous underside …. this is what is important when gluing to walls and floors …. it sucks up moisture , the glue wont hold onto a glossy impervious surface.