Israeli Defence Minister Moshe Yaalon said on Monday he was skeptical that a Syria ceasefire announced for February 27 by the United States and Russia will succeed.
He also said that both Washington and Moscow recognize Israeli freedom of action in Syria, where Israel is reported to have carried out a series of raids over the past five years.
"It is difficult for me to see a ceasefire while Daesh (the Islamic State group) and Al-Nusra Front (the Syrian Al-Qaeda affiliate) are not part of the process and the Russians say they will strike both organizations," a statement said.
The Syria ceasefire is due to take effect on February 27 at midnight Damascus time (2200 GMT Friday), according to a joint US-Russian statement released by the State Department in Washington.
Since the conflict began in 2011, Israeli forces are reported to have attacked positions of President Bashar al-Assad's forces and his allies from Israel's arch-foe Hezbollah.
"Israeli action is based on a single principle: self-defence," the statement from Yaalon's spokesman said.
"It is well-known in both the United States and Russia, which is currently acting in Syria, that our freedom of action and defence of our interests continue."
The minister was speaking to an Israeli journalist aboard American warship the USS Carney at Haifa, northern Israel.