Abdul Haq Baloch, 37, a television journalist was shot dead on Saturday in the Baloch town of Khuzdar while he was driving home from work.
Protests were held across several cities to condemn the killing today.
The national body for journalists of Pakistan called for more countrywide protests after cases were registered against 26 journalists protesting Baloch's death in Quetta.
"They have registered police cases against us today instead of finding the killers of Abdul Haq," Ovais Tohid the news head of ARY television channel said.
The Pakistan Federal Union of Journalists condemned the registration of cases against protesting journalists and said the protests would continue tomorrow.
An official of PFUJ said the government needed to provide protection and security to working journalists in Balochistan and the Khyber Pakhtukhwa provinces where working conditions were difficult.
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"Journalists receive death threats on daily basis," another official said.
Nadeem Gorgnari, president of the Khuzdar press club confirmed that Abdul Haq had also been getting death threats since last week.
Police said masked men opened fire on his car around 100 yards from the local press club.
"He died as a result of his bullet wounds and we are investigating the case," Haq Nawaz a senior police official said.
Nawaz said police have registered a case against "unidentified gunmen".
Pakistan has been ranked as the deadliest country for journalists by international media watchdogs.