Supreme Leader Ayatollah Ali Khamenei addresses in a televised speech.
Iran President Hassan Rouhani has blamed Israel for the killing of a top nuclear scientist on Friday, and said it would not slow down the country's nuclear programme.
Rouhani also said Iran would retaliate over Mohsen Fakhrizadeh's killing at a time of its choosing. An Israeli cabinet minister said he had "no clue" who was behind the ambush by gunmen on Fakhrizadeh's car, the BBC reported on Saturday.
Israel has previously accused the physicist of being key to a covert nuclear weapons programme.
Fakhrizadeh was Iran's most renowned nuclear scientist, who headed the ministry of defence's research and innovation organisation.
His killing threatens to escalate tensions over Iran's nuclear programme with the US and its close ally Israel.
President Rouhani said on Saturday his country would respond "in due course" but that Fakhrizadeh's killing would not push Iran into making hasty decisions.
"Iran's enemies should know that the people of Iran and officials are braver than to leave this criminal act unanswered," he said in a televised cabinet meeting.
"In due time, they will answer for this crime," he added.
In an earlier statement, the president accused the "the mercenaries of the oppressive Zionist regime" - referring to Israel - of being behind the attack.
"The assassination of martyr Fakhrizadeh shows our enemies' despair and the depth of their hatred... His martyrdom will not slow down our achievements."
Iran Supreme Leader Ayatollah Ali Khamenei also called for the "punishing" of the perpetrators of the attack "and those who commanded it", in a tweet on Saturday.
His military adviser, Hossein Dehghan, had earlier vowed to "strike" the attackers like thunder.
(Only the headline and picture of this report may have been reworked by the Business Standard staff; the rest of the content is auto-generated from a syndicated feed.)
Business Standard has always strived hard to provide up-to-date information and commentary on developments that are of interest to you and have wider political and economic implications for the country and the world. Your encouragement and constant feedback on how to improve our offering have only made our resolve and commitment to these ideals stronger. Even during these difficult times arising out of Covid-19, we continue to remain committed to keeping you informed and updated with credible news, authoritative views and incisive commentary on topical issues of relevance.
We, however, have a request.
As we battle the economic impact of the pandemic, we need your support even more, so that we can continue to offer you more quality content. Our subscription model has seen an encouraging response from many of you, who have subscribed to our online content. More subscription to our online content can only help us achieve the goals of offering you even better and more relevant content. We believe in free, fair and credible journalism. Your support through more subscriptions can help us practise the journalism to which we are committed.
Support quality journalism and subscribe to Business Standard.