Yes Anoop, You have to pay Service tax on import of services. Read the provision below:
The statutory provisions use the words ‘Services provided from outside India and received in India’. However, generally, the tax is known as tax on ‘Import of Services’.
Section 66A(1) (effective from 18-4-2006) provides that where any service specified in section 65(105) of Finance Act, is,— (a) provided or to be provided by a person who has established a business or has a fixed establishment from which the service is provided or to be provided or has his permanent address or usual place of residence, in a country other than India, and (b) received by a person (hereinafter referred to as the recipient) who has his place of business, fixed establishment, permanent address or usual place of residence, in India, such service shall, for the purposes of this section, be taxable service, and such taxable service shall be treated as if the recipient had himself provided the service in India, and accordingly all the provisions of this Chapter shall apply.
Further i dont think u have to amend ur registration Certificate. Check it
Regards
CA Dillip