Economic sanctions are mainly used to?

Economic sanctions are mainly used to "punish nations that disobey international law".

A sanction is a punishment imposed on another nation, or on individual natives of another nation. It is an instrument of remote arrangement and monetary weight that can be depicted as a kind of carrot-and-stick way to deal with managing universal exchange and legislative issues.  

Economic sanctions are characterized as the withdrawal of standard exchange and money related relations for outside and security strategy purposes. They might be extensive, denying business movement as to a whole nation, similar to the long-standing U.S. ban of Cuba, or they might be focused on, blocking exchanges of and with specific organizations, gatherings, or people.

ayatollah khomeini can best be described as the leader who declared iran to be an islamic republic.