Exemption of Pure Service :-
"Pure services (excluding works contract service or other composite supplies involving supply of any goods) provided to the Central Government, State Government or Union territory or local authority or a Governmental authority by way of any activity in relation to any function entrusted to a Panchayat under article 243G of the Constitution or in relation to any function entrusted to a Municipality under article 243W of the Constitution"
2. Pure service provided to Central Govt which have no correlation to article 243G of the Constitution or article 243W of the Constitution activities, are taxable to normal course.
3. Manpower recruitment agency is required to collect GST with normal rate (if point 2 applicable)
You have also deducted TDS as per Section 51 of CGST Act.