Afghan special forces suppressed the attack on Shamshad TV after two hours, but police said at least two people had been killed and 20 wounded.
"People dressed in police clothes came in and initially threw hand grenades, which killed one of our guards and wounded another," Abed Ehsas, Shamshad's news director told broadcaster Tolo News TV.
"After that, others got into our building and started firing. Some of our colleagues were hit, though, thank God, many others managed to get out. Some were wounded by gunshots, falling glass and when they jumped from high floors."
Najib Danish, spokesman for the Interior Ministry, said the two casualties were a male and a female security guard at Shamshad TV.
"There were two attackers and both have been killed," Mr Danish said shortly after the attack, adding that the police have sealed off the station and were combing the premises.
He said the police rescued some of the TV staff as the attack was unfolding but he did not elaborate.
During the attack, a special forces unit blasted a hole in the concrete wall around the compound and entered the site amid a crack of gunfire.
At least one attacker was killed during the operation, while another was killed at the compound entrance.
In a statement on its news agency Amaq, Isis claimed to have killed as many as 20 people, without providing evidence.
The group, based mainly in the eastern province of Nangarhar, has claimed a number of attacks on civilian targets in the Afghan capital.
It often inflates reports of its atrocities in propaganda.
The Taliban denied responsibility for the attack.
The attack took place about three weeks after a series of attacks including one on a Shia mosque in Kabul in which more than 50 people were killed.
Shamshad TV halted normal programming during the attack, transmitting only a still image. But it resumed broadcasting after about two hours, saying the attack had ended and staff trapped in the had been building rescued by police.
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