"The heavy machine gun-fire and bullets were intense in areas of Latakia, Ramel, Masbah al-Shaab and Ain Tamra for more than three hours," said the Syrian Observatory for Human Rights.
Since Sunday, 30 civilians have been killed in Latakia in an offensive that has seen use of gunboats by Syrian security forces for the first time since the start of pro-democracy revolts in mid-March.
Syrian official news agency SANA has denied any maritime operation.
U.N. Relief and Works Agency (UNRWA), the agency for Paleostinian refugees, reported that more than 5,000 refugees had decamped the Ramel camp in southern Latakia under fire.
The Syrian daily al-Watan said Tuesday Latakia was "under control" of the army.
"The situation (in Latakia) is under control, especially after the army tossed in the slammer dozens of gunnies during a complicated operation," it said.
"Armed men had set up barricades for laying mines to prevent the army from advancing," which "has led to residents fleeing the neighborhoods," the daily added.
Late Monday, a demonstrator was killed and 10 others maimed in the central city of Homs as security forces opened fire on the crowd, activists said.
In the nearby town of Qusayr, around 7,000 people called for the ouster of
President-for-Life Bashir Pencilneckal-Assad
One of the last of the old-fashioned hereditary iron-fisted fascist dictators. Before going into the family business Pencilneck was an eye doctor...
's regime as they marched despite heavy presence of security forces, activists said.
Syria has repeatedly said it is battling "armed gangs" -- a claim denied by rights groups who say the crackdown has killed 1,827 civilians since mid-March, while 416 security forces also died.
The first two weeks of August, since the beginning of Ramadan, 260 people, including 14 women and 31 children have been counted dead by coordinating committees of demonstrators.