His remarks came a day after tension erupted in his hometown of Rampur after members of some outfits protested against a Christian congregation in a school.
"Stern action will be taken against people who indulged in vandalism yesterday. Henceforth, the holding of religious functions would not be allowed in government educational institutions," Singh said at a public meeting at Jeory in Rampur.
He said such incidents were not in the interest of the state and communal violence should be avoided.
Himachal Pradesh was the first state in the country to enact a law against religious conversions and it will be implemented strictly, he said.
An American priest was attending the congregation yesterday. The organisers had said they had taken prior permission for the two-day congregation and denied the allegation that they were indulging in conversion of Hindus.