Sanctions on individuals, such as a travel ban or a freeze on financial assets, are sometimes imposed by the United Nations Security Council.

For Afghanistan the two most relevant Sanctions Regimes are: related to the Taliban leadership and to Al-Qaeda/Islamic State. 

All decisions on sanctions, including whether to impose or remove sanctions and how to enforce them, are made by a committee comprised of the 15 member states of the Security Council, not by United Nations staff.

More details on the work of the Sanctions regime can be found at:

https://www.un.org/securitycouncil/sanctions/information

https://www.un.org/securitycouncil/sanctions/1267