JERUSALEM (Reuters) - Israeli military officials were quoted on Monday rowing back from an assertion by the defense minister that Hezbollah was behind a spate of shelling from Syria, which could increase tension on Israel s northern frontier. The government of Prime Minister Benjamin Netanyahu has been warning that Israel, which has largely stayed out of the six-year-old Syrian civil war, could step up attacks in retaliation for shelling across the frontier, or to block Damascus s Iranian and Lebanese Hezbollah reinforcements from setting up bases. That could thrust the Israelis into confrontation with Syria and potential run-ins with its big-power backer, Russia. Israel last battled Hezbollah in Lebanon in 2006, and has occasionally fired on Syria to attack what it said were Hezbollah or Iranian targets during the civil war, but has mainly avoided direct fighting against Syria since their last war in 1973.    Twice last week, mortar rounds or rockets launched from Syria hit areas of the Israeli-held Golan Heights, causing no casualties but drawing Israeli artillery fire against Syrian army posts. Addressing his parliamentary faction on Monday, Defence Minister Avigdor Lieberman, a far right politician, said the Golan shelling was carried out by a Syrian cell on Hezbollah s orders without Damascus having been informed, to stoke Israeli-Syrian fighting. Lieberman did not detail the source of his information.  There was a personal instruction by (Hezbollah leader Hassan) Nasrallah to compartmentalize Assad and his regime from the execution of this shooting ... with the goal of dragging us into the Syrian mire,  Lieberman said in the televised remarks.  Therefore I call here both on the Assad regime ... and also on the Russian forces that are present there, to restrain Hezbollah.   Within hours, every major Israeli media outlet aired remarks attributed to unnamed military officers casting doubt on Lieberman s account.  We have no information supporting Lieberman s statement purporting that the (Syrian shelling) cell was run by Hezbollah personnel,  the top-rated Channel 2 television quoted  sources in the IDF (Israel Defence Forces)  as saying.  Lieberman s office   did not immediately respond to  the comments contradicting him. A Lieber man confidant who requested anonymity told Reuters :  The defense minister spoke based on his own judgment and assessment.  Hezbollah did not respond to Lieberman s allegations, but its affiliated TV station Al-Manar noted the Israeli media dissent. In what appeared to be a reference to Israel s efforts to coordinate its actions in Syria with Moscow, Lieberman said Russian military commanders in Syria  have received all the (information) that they need on this matter . There was no immediate comment from officials in Moscow. Syria s Foreign Ministry said after Saturday s exchange of fire on the Golan that Israeli strikes would have  grave consequences . Lieberman says Israel is doing everything in its power to stave off military confrontation on the northern front. 