This is very normal at this age.
Here are two other options on wake to sleep - so instead of waking them you just help them get into the next sleep cycle.
Jane (one of the nap moderators) did this w/ success for her king of short naps. I set my timer, in case I got busy. When it near the time, I oh-so quietly crept into his bedroom, once he stirred, I placed one hand on his back and one of his thigh. I didn't say anything, make any sound. Just as subtle as possible. I stayed like that until he returned to deep sleep, and slowly lightened the pressure of my hands.
Here is what i did: set my timer for 40min (for 30min if your LO wakes then) and crept into her room. I had a drawer full of paci's so I didn't have to dig in the crib for it. As soon as she stired, I lightly put the paci to her lips. She took it, i would move out of sight and sometimes she would right back to sleep. If she opened her eyes and saw me, forget it. I would have to do shh/pat for 15-30mins to get her back to sleep.
This strategy is not a quick fix but take time to perfect so don't give up too soon.
Also have a read at the sticky on top of this page: "teaching newborns to sleep".