Fishermen's protest went on as negotiations with authorities remained inconclusive on Tuesday, the 24NewsHD TV channel reported.
The fishermen have been on protest against the authorities for limiting fishing. The protesters have closed the port.
Talks between reps of fishermen and the authorities were held at the head office of Karachi Port Trust but the government failed to woo the protesters.
The strike affected business at one of the largest and busiest deep-water seaports of South Asia.
The PM special aide said another round of talks will be held in the morning. He claimed that the Baluchistan admin is in contact over the matter.
Reportedly, fishermen anchored their boats to block the shipping channel of the port, leaving scores of cargo ships anchored outside the port.
In August last year, the fishermen went on strike as they were barred from going into the open sea for fishing.
They said they were unable to do fishing by placing limits making it difficult for them to make both ends meet.