UN Security Council Resolution 1747 does forbid Iran from selling arms: "Iran shall not supply, sell, or transfer directly or indirectly
from its territory or by its nationals or using its flag vessels or aircraft any arms or related materiel, and that all States shall prohibit the procurement of such items from Iran by their nationals."
But Israel offered no proof for its contention that their ultimate destination was the hands of Hezbollah, which fought a brief war against Israeli forces in southern Lebanon in 2006. That war ended with a cease-fire monitored by the UN Interim Force in Lebanon (UNIFIL), which is charged with interdicting arms shipments in Lebanese territorial waters and inside the country. A UNIFIL spokesman said the group considered the charge the weapons were destined for Hezbollah as yet "unproven."
Israel has, on a number of occasions in the past few years, hinted that it would be willing to unilaterally attack Iran's nuclear sites if it grows convinced that Tehran's nuclear program cannot be curtailed by other means. Iran, which has only a small number of missiles with sufficient range to strike out at Israel, has cultivated ties with Hezbollah – fellow Shiites – in the past decade, and security analysts say it sees the threat the militant group poses to northern Israel as part of its deterrent against an Israeli attack.
Israel's Haaretz newspaper reported that the "Foreign Ministry issued a document to Israeli embassies and consulates around the world on Wednesday, instructing diplomats to utilize Israel's seizure of the ship to direct international pressure toward Iran."
Netanyahu made clear in his comments on Thursday that Israel wants the focus to be on Iran, which has been threatened with new sanctions by President Barack Obama if progress isn't made in curtailing the growth of its nuclear program by the end of the year. Israel alleges Iran is seeking to build a nuclear bomb, something which it argues would pose an existential threat.