You can't impose sanctions on a head of state??

In defending the US decision to confine the sanctions to "cronies" of the Russian president--whatever that means, and is Kerry a crony of Obama--a White House official was quoted by Dana Milibank as saying that the US could not impose sanctions on Putin because he is a head of state and that you can't do that. Excuse me but did the US not impose sanctions on Bashshar, his mother, his brother, his cousins, and his sister?