Iranian President Hassan Rouhani Saturday said the Israeli Occupation seeks to cause 'chaos' by assassinating the prominent Iranian nuclear scientist Mohsen Fakhrizadeh. He accused the occupation of assassinating Fakhrizadeh and that Iran will retaliate at 'the proper time'.

"Once again, the wicked hands of the global arrogance, with the usurper Zionist regime as the mercenary, were stained with the blood of a son of this nation," Rouhani said in a statement on his official website, referring to Fakhrizadeh's killing.

"The assassination of martyr Fakhrizadeh shows our enemies' despair and the depth of their hatred... His martyrdom will not slow down our achievements," he added.

Iranian authorities threatened to avenge the assassination of Fakhrizadeh's, who was killed Friday.

The Israeli Occupation's Prime Minister Benjamin Netanyahu's office said it would not comment on the attack. However, Netanyahu once called out Fakhrizadeh's name in a news conference, saying 'remember that name', which fueled speculation of their involvement.

Rouhani described the death of Fakhrizadeh as a 'heavy loss'.

Iran's Supreme Leader Ayatollah Ali Khamenei Saturday promised to retaliate for the assassination of an Iranian nuclear scientist Mohsen Fakhrizadeh. He added that his nuclear work would continue.

He called for "following up on this crime and certainly punishing the perpetrators and those responsible."

He tweeted Saturday, "One of our country’s eminent scientists in the nuclear & defense fields - Dr. Mohsen Fakhrizadeh -has been martyred by brutal mercenaries. With his great, enduring scientific efforts, he sacrificed his life on the path of God & the lofty status of martyrdom is his divine reward."