Do you consider Berber/Imazighen people pure Africans and could they be apart of pan-African movement In your opinion?

Short Answer:
No, I don’t.
Unless we are refering to the “Afro-Berbers” or the “Black Berbers."  The original Berbers, or North Africans were Black, the current individuals who claim that title are often not.

Long Answer:
The Berbers are not a homogenous group but many of them are descendants of invaders and colonizers and tend to embrace
Arabic and Islamic Culture over Pan-Africanism.  Islam has been at war with Africa and Africans longer the Christianity and the Europeans so I don’t think there are any long-term allies to be found among the "White Berbers." 

Even though the White Bebers have occupied North African since the 7th Century they have fought to distinguish themselves from "Black Africa” for the most part so the onus is not on the Aborigional African to extend ourselves or seek unity with the Berbers/Imazighen; it is on them to decide if their loyalties lay with Africa as a whole, their occupied segment of African, or with the many enemies of Africa, especially the enemies in the East and Islamic World. 

“Everyone who is in African who cannot be identified as an African is an invader, and has waged war against African people and culture!” – Dr. John Henrik Clarke (paraphrase.)

Some further insights from the Good Dr. Clarke: