The injured include six tourists and nine sadhus, Haridwar Kotwali incharge Mahendra Singh Rana said.
Six buses carrying tourists from Delhi were parked haphazardly outside Bhairav Mandir blocking the passage to the temple.
When sadhus of Juna Akhara objected to it, the tourists got angry and allegedly beat up one of them.
This enraged the sadhus and the two groups resorted to stone-pelting which left 15 persons injured, Rana said.
Both the groups have lodged a complaint against each other, he said.