Mohamed Moalim Abdirahman, a security official in central Somalia's Galgadud region, said on Thursday that the men appeared "healthy" despite their ordeal, but that the pirate gang still held as many as nine other hostages, all believed to be from Iran, AFP reported.
"Security forces rescued four Iranians who have been held hostage by pirates," said Abdirahman said.
"Two of the kidnapers were arrested during the raid on a house where they held the victims," he added.
It was not immediately clear when the crew were seized by pirates, or which vessel they came from.
Piracy peaked in 2011, when Somali pirates held over 700 hostages, but rates of attacks have tumbled, prompted partly by the posting of armed guards on boats and navy patrols.