The attacks come after a week-long battle between Alawite fighters in Tripoli's Jabal Mohsen neighborhood and Sunni militants in the neighboring Bab al-Tabbaneh area that killed 14 people from both sides, AFP reported.
Nine Alawite workers were wounded on Saturday when Sunni gunmen stopped the bus they were travelling in and opened fire.
"The gunmen opened fire at the bus and then beat some of the workers travelling in it. All nine Alawites had either gunshot or beating wounds and were taken to hospital for treatment," the security official said.
"The bus they were on stopped at the entry of (Tripoli's Sunni) Bab al-Tabbaneh. That's when the gunmen attacked," the official added.
A doctor who treated the men said none had been injured critically.
Three more Alawites suffered knife wounds on Saturday after they were attacked by unknown men in Tripoli's central Tal Square.
Another man, who works for the city municipality, was also attacked by a knife-wielding assailant in a separate incident.
Earlier this week, six other Alawites were wounded in attacks against the community in the city.
Tripoli is Lebanon's second city and is the scene of frequent Syria-linked battles that pit Sunnis from Bab al-Tebbaneh against Alawites in Jabal Mohsen.
Most Sunnis support foreign-backed militants fighting against Syrian President Bashar al-Assad, while Alawites, who belong to the same sect as Assad, support his government.
The latest fighting ended when the army deployed along Syria street, which separates the two districts and acts as the makeshift frontline.
Tripoli's population is 80 percent Sunni and 11 percent Alawite.
Speaking to AFP on condition of anonymity, a barber from Jabal Mohsen who works in central Tripoli said he is afraid of going to work.
"Ever since the latest battle ended, I've received threats by phone. I'm scared of going to (central) Tripoli. I'm thinking of closing my shop down," he said.
Many of Tripoli's residents long for peace, as every fresh outbreak of violence forces schools and universities to close.
"I condemn these attacks (against Alawites)," said 35-year-old Sunni resident, Khaled al-Rafei.
"What happened today is bad and the state must detain whoever was behind the attacks, whatever their political or sectarian affiliations."
Tripoli suffered horrific car bomb explosions near two mosques in August, killing 45 people.
HH/HH