Iran signed a treaty and got technical assistance because they signed. They are obligated to their word irregardless of whether Israel agrees to the treaty. Those that sign the treaty are obligated and are deserving of punishment for the violations, irregardless of the non-signatories. What kind of law obligates a country to sign a treaty? Iran can be punished for their flagrant violation of the treaty. Period. Israel is not a signatory and thus has no obligations.
U.S. to defend Syrian rebels with airpower, including from Assad (Reuters)
from the article: Obama: Israel should sign nuclear non-proliferation treaty