Jerusalem - Israel signalled on Thursday it would not hasten into any open conflict with Iran or its Lebanese guerrilla ally Hezbollah despite blaming them for a deadly attack on its citizens in Bulgaria.
A suicide bomber killed eight people on a bus carrying Israeli tourists in Burgas airport, drawing a promise by Prime Minister Benjamin Netanyahu to "react powerfully" to what he called "Iranian terror".
Sofia officials have not publicly said who they think ordered the bombing, nor has there been comment from Iran or Hezbollah.
Israel's allegation, based on suspicions that Iranian and Hezbollah agents have been trying for years to score a lethal strike on its interests abroad, triggered speculation in local media that the Netanyahu government might now hit back hard.
The Israelis have long threatened to resort to military force to curb Tehran's disputed nuclear programme, but Defence Minister Ehud Barak sounded more restrained on Thursday about a response to the Bulgaria attack.
Speaking on Israel Radio, he said the country would "do everything possible in order to find those responsible, and those who dispatched them, and punish them" - language that appeared to suggest covert action against individuals.
President Shimon Peres said on his Facebook page that Israel would "take action in every terror nest, worldwide. It has the means to do so, and we are determined to act in this spirit."
Israel may be reluctant to cross Western partners by rushing into a full-on confrontation which would stretch its military capabilities and possibly draw Iranian escalation against U.S. interests as well as disruptions of the global oil supply.
A clash with Hezbollah, which the Israeli military says has stockpiled as many as 80,000 rockets in south Lebanon, carries the risk of igniting that frontier at a time when the Netanyahu government is worried about turmoil in neighbouring Syria.
Giora Eiland, a retired Israeli army general who served as national security adviser from 2003 to 2006, played down the prospects of the Bulgaria bombing spilling over into war.
"I think that any response, whatever it may be, will not be an immediate response," Eiland told Israel Radio separately.
"Any response, whatever it may be, will not be in the form of an air force operation, or strike - certainly not in Iran over this matter, nor in Lebanon."
Barak, whose remarks focussed on Hezbollah's alleged role in the Bulgaria bombing, described it as the bloodiest of a series of recent plots against Israelis, including diplomats, abroad.
Iran denied involvement in the previous attacks but some analysts believe it is trying to avenge the assassination of scientists from its nuclear programme, which it blamed on Israel and Western allies. Iran says its atomic ambitions are peaceful, denying foreign charges of secret military designs.
Hezbollah has its own scores to settle with Israel. Two years after their 2006 border war, the Lebanese Shi'ite militia lost its commander, Imad Moughniyeh, to a Damascus car bomb it said was the work of Israeli spies, and vowed revenge.
Netanyahu's national security adviser from 2009 to 2011, Uzi Arad, confirmed that Israel killed Moughniyeh - though the country has never formally claimed responsibility.
Speaking to Israel's Army Radio, Arad described the Bulgaria bombing as part of a "dynamic of escalation" but counselled the Netanyahu government to invest in better intelligence and security.
He said "risk management" was required and that Wednesday's bloodshed may be an "unavoidable price" of the internal and international pressure building on Iran and its allies.