Committee to Protect Journalists (CPJ) has written to Sharif to revoke the suspension of ARY News, accused of airing a "derogatory" programme against the country's judiciary.
The channel was suspended for 15 days and Pakistan also imposed a fine of 10 million Pakistani rupees on it.
The Pakistan Electronic Media Regularity Authority (PEMRA) suspended ARY News' licence yesterday, accusing it of "maligning" the country's judiciary in a talk show, 'Khara Sach', which was critical of the court system and senior judges.
"We ask that you do what is in your power to restore ARY News consistent with the pledges you made to our delegation and the people of Pakistan to promote press freedom and open media," he said.
"In June, the privately-owned Geo News, was ordered off the air and fined by PEMRA after the channel aired allegations that the Inter-Services Intelligence, Pakistan's powerful intelligence agency, was behind the attack on anchor Hamid Mir," it said.
"Since then, Geo has been restored to the airwaves, but its management says that distribution has significantly decreased," according to The New York Times.