The six are believed to be held in the Ain Hilwe Palestinian refugee district outside the Lebanese port of Sidon.
The officials in the Lebanese port of Junieh said the ferry, the Empress, was stopped off the Lebanese coast.
Israel has bombed the airport and routes from Syria, and has put a sea blockade on Lebanese ports.
Israeli fighter-bombers mounted broad attacks today against Palestinian guerrilla strongholds near the southern Lebanese port of Sidon.
They are believed to be held in a Palestinian refugee camp near the Lebanese port of Sidon.
The boat, intercepted outside the Lebanese port of Khalde, was taken into custody with its passengers and crew.
From time to time, Israeli forces searched ships bound to or from Lebanese ports.
The Lahav took part in the 2006 Lebanon War by blockading Lebanese ports.
Today, the highway and railroad in Homs to the Lebanese port of Tripoli run through the gap.
Accounts by both sides said the incident occurred off the southern Lebanese port of Tyre.