Mashal, a journalism student at the Khan Abdul Wali Khan University in Mardan in Khyber-Pakhtunkhwa, was stripped, beaten and shot in the head and chest by the mob on Thursday.
Mashal Khan and another student were set upon on April 13.
Responding to a question about the political affiliations of arrested suspects, the IGP said the police would only focus on the accused.
The Police said that Mashal was accused of running Facebook pages which allegedly published blasphemous content.
A student said many leaders of the university's student bodies were part of the mob that attacked the two students.
The mob instead seems to have been incited by rumours circulating among the university's student body.
Following the incident, university authorities have shut down the campus indefinitely and vacated the hostels.
In press conference, senior official says 22 people, including six university officials, have been arrested thus far..
Meanwhile, the daughter of Prime Minister of Pakistan Maryam Nawaz Sharif also released her statement to condemn the murder of young student stating that she was shocked to see Mashal Khan killing video.
Mashal, a student of Mardan's Abdul Wali Khan University, was torched to death by a mob over accusations of blasphemy on Thursday.
Blasphemy is a highly sensitive and incendiary issue in Pakistan.
Two other students were also wounded in the violent attack after being accused of committing blasphemy against Islam.
Mardan police chief Mohammad Alam Shinwari denied the allegation that officers did not do enough to save Khan.
Critics say blasphemy laws, which allow the death penalty in some cases, are often misused to oppress minorities. "I was alerted that they were approaching, so I closed the gates". At least 65 people have been murdered over blasphemy allegations since 1990, according to a Center for Research and Security Studies report.
A local imam had refused to lead Khan's funeral prayers on Friday.
However, Pakistan's government has been vocal about blasphemy in recent months, with Sharif issuing an order in March for the removal of content deemed blasphemous online and threatening "strict punishment" for those violating the law.