The militants fled after hurling the grenade at around 9 pm last night when Mobi was present at the house.
An AMWJU spokesman said a militant group, the name of which was being withheld, had issued a press statement a few days ago threatening certain individuals after levelling charges against them and wanted media houses to publish it.
As the statement was against the guidelines of the Press Council of India, media houses refused to publish it angering the outfit that threatened journalists with dire consequences for disobeying their diktat, he said.
After the grenade attack, a team of editors and senior journalists went to Home Minister Gaikhangam's residence late last night and apprised him of the incident.
Gaikhangam asked the police to nab the culprits but they were yet to be arrested, the spokesman said adding that scribes have condemned the incident at an emergency meeting.
Official sources said security measures were tightened at media houses and residential areas of the editors following instruction from the home minister.
The AMWJU spokesman said several editors of local dailies received emails by this particular outfit cautioning them to be careful while moving on the roads.
Other militant outfits had also issued threats to media houses if their statements were not published, he said.