The man had been charged, but was later released pending further inquiries without appearing in court.
Faslane, on the Gare Loch about 25 miles (40km) north-west of Glasgow, is the home of the Royal Navy’s nuclear-powered submarine fleet.
Those include the UK’s four Vanguard-class ballistic missile submarines which carry Trident nuclear missiles.
The March arrests came a few weeks after the US and Israel attacked Iran at the end of February.
The Crown Office said: “The Procurator Fiscal received a report relating to a 34-year-old man and an incident said to have occurred on 19 March 2026.
“After careful consideration of the facts and circumstances of the case, including the available admissible evidence, the procurator fiscal decided that there should be no proceedings taken at this time.
“The Crown reserves the right to proceed in the future should further evidence become available.”
