Navy spokesman General Ayoub Qassem said the gunmen in a speedboat chased the dinghy yesterday, boarded it around five nautical miles off the town of Zuwara and stole the migrants' possessions.
The migrants from sub-Saharan Africa, including 27 women and two children, were stranded at sea for several hours before being rescued by Libyan coastguard alerted by a local fisherman, Qassem told AFP.
The International Organisation for Migration said a total of 371 migrants were rescued yesterday thanks to the intervention of fishermen in three separate incidents off Zuwara.
"This type of operation takes a lot of time. We don't have the means," said Qassem, calling for international relief groups to provide Libya with boats and equipment to save more migrant lives.
In the first three months of 2017, more than 24,000 migrants arrived in Italy after making the perilous crossing from Libya, up from 18,000 in the first quarter of last year, according to the UN refugee agency UNHCR.