An Iranian general killed in an Israeli air strike in Syria was not its intended target, and Israel believed it was attacking only low-ranking guerrillas, a senior security source said on Tuesday.
The remarks by the Israeli source, who declined to be identified because Israel has not officially confirmed it carried out the strike, appeared aimed at containing any escalation with Iran or the Lebanese Hezbollah guerrilla group.
Iranian Revolutionary Guard General Mohammed Allahdadi was killed with a Hezbollah commander and the son of the group's late military leader, Imad Moughniyeh, in Sunday's attack on a Hezbollah convoy near the Israeli-occupied Golan Heights.
Hezbollah, which is backed by Iran and fought a 34-day war with Israel in 2006, said six of its members died in the strike.
Tehran has vowed to strike back. "These martyrdoms proved the need to stick with jihad. The Zionists must await ruinous thunderbolts," Revolutionary Guards' chief General Mohammad Ali Jafari was quoted on Tuesday as saying by the Fars news agency.
Asked if Israel expected Iranian or Hezbollah retaliation, the source said: "They are almost certain to respond. We are anticipating that, but I think it's a fair assumption that a major escalation is not in the interest of either side."
Troops and civilians in northern Israel are on heightened alert and Israel has deployed an Iron Dome rocket interceptor unit near the Syrian border.
"We did not expect the outcome in terms of the stature of those killed - certainly not the Iranian general," the source said. "We thought we were hitting an enemy field unit that was on its way to carry out an attack on us at the frontier fence.
"We got the alert, we spotted the vehicle, identified it was an enemy vehicle and took the shot. We saw this as a limited tactical operation."
In an Israeli television interview, Defense Minister Moshe Yaalon stopped short of claiming responsibility for Sunday's air strike while describing those killed as "bad guys, all of them".
"We are not fearing, but nevertheless we should be ready for, any act or any action and even for any escalation," Yaalon told the English-language station i24 News.
Israel has struck inside Syria several times since the start of the Syrian civil war, mostly destroying weaponry such as missiles that Israeli officials said were destined for Hezbollah, Israel's longtime foe in neighboring Lebanon.
Hezbollah has been fighting alongside President Bashar Assad's forces in the four-year-old Syrian conflict.