Pakistan's Taliban described Yousufzai as a "spy of the West".
"For this espionage, infidels gave her awards and rewards. And Islam orders killing of those who are spying for enemies," the group said in a statement.
"She used to propagate against mujahideen (holy warriors) to defame (the) Taliban. The Quran says that people propagating against Islam and Islamic forces would be killed.
"We targeted her because she would speak against the Taliban while sitting with shameless strangers and idealized the biggest enemy of Islam, Barack Obama."