not to my knowledge. Increased ammo is only available for shotguns and SMGs. Sniper rifles get increased armour penetration and increased headshot damage bonuses instead.
It is possible to ever so slightly increase your ammo by using the +ammo equipment (bonus 10% ammo) bought from somewhere (Citadel iirc).
There are 3 sniper rifles in the game, the 2nd one you find, the viper whatever its called, has 60 shots 12 per thermal clip, but I forget where you get it. Its pretty hard to miss though. Thats one way to increase your sniper rifle ammo