Iran’s message was delivered to Israel via Hungary's Foreign Minister who called Katz directly to relay the information.

Iran has decided to attack Israel, Foreign Minister Israel Katz announced amid an intense diplomatic push to avoid any further military action that could spark a direct war between the Islamic Republic and the Jewish state.
Iran’s message was delivered to Israel through Hungary's Foreign Minister Péter Szijjártó, who called Katz directly to explain that he had received this information from acting Iranian Foreign Minister Ali Bagheri.
"Iran has informed us that it intends to attack Israel,” Katz said, adding that ”The world should exact a price from Iran for any aggressive action it carries out.”

In a conversation Bagheri held with his Bahraini counterpart Abdullatif bin Rashid Alzayani, he spoke of his country’s determination to respond to the assassination of Hamas political leader Ismail Haniyeh in Tehran last week.
Israel has not claimed responsibility for the attack but is widely presumed to have carried it out.

“Silence toward the expanding evil acts of the Zionist regime will be detrimental to the regional stability, adding that indifference to its recent moves is tantamount to giving the regime an incentive.”
The United States believes that an Iranian attack could come as soon as the next 48 hours.