A human rights group said the two were killed when government forces shelled the opposition stronghold of Homs.
In Paris, French government spokeswoman Valerie Pecresse said those killed were French photojournalist Remi Ochlik and American veteran war reporter Marie Colvin, who was working for Britain's Sunday Times.
At least 19 people were killed in Wednesday's shelling, including the journalists, activists said.
The Syrian military has redoubled its attacks on Homs in the past few days, aiming to retake neighborhoods that have come under control of the opposition and armed rebels - many of them military defectors.
The seizure of territory and nearly daily clashes between the rebels and regime forces have pushed Syria to the brink of all-out civil war.
Meantime, U.S. Secretary of State Hillary Rodham Clinton is heading to North Africa this week to meet with foreign leaders to discuss Syria.
Some countries are beginning to explore the possibility of arming Syrian rebels.
The U.N. says President Bashar Assad's government crackdown has killed more than 5,400 people in the last year.
The Associated Press contributed to this story.