Iran's Vice President Mohammad Reza Aref has strongly condemned the assassination of Hamas political chief Ismail Haniyeh, calling it "another manifestation of state terrorism" of Israel.
While Hamas and Iran blamed Israel for the killing, Tel Aviv has not yet confirmed or denied its involvement.
Aref said the targeted assassination of Haniyeh was "one of the consequences of the silence of the international community over continued crimes of the Zionist regime and the clear violation of international laws."
According to Iranian media, the attack targeting the Hamas leader reportedly took place at a guesthouse for war veterans in northern Tehran managed by the Islamic Revolutionary Guard Corps (IRGC).
The IRGC confirmed the assassination of Haniyeh and one of his bodyguards, saying an investigation into the killing was currently underway.
Haniyeh was in Tehran to attend the swearing-in ceremony of Iran's newly elected President Masoud Pezeshkian on Tuesday and was scheduled to return to Doha on Wednesday.
"We condemn this criminal act and, following the reports of the relevant institutions, will pursue this issue with seriousness and strength so that they do not feel they can harm the Islamic Republic of Iran at the onset of the National Unity Government," Aref, appointed by Pezeshkian as his first deputy earlier this week, said during a Cabinet meeting in Tehran.
He said Iran had the "honor" of hosting the slain Hamas leader at President Pezeshkian's formal inauguration ceremony, which "increases our sorrow."
Aref stressed that "the resistance front will continue on its path," and reaffirmed Iran's support for the "oppressed people of Palestine."
The Iranian government has declared three days of national mourning following Haniyeh's assassination.
In a statement, the Iranian government said the Hamas leader's assassination has "caused grief to the Islamic nation, the devotees of the resistance movement, and all the free people of the world."
Earlier on Wednesday, Iran's Supreme Leader Ayatollah Ali Khamenei said the country considers it a duty to "avenge the dear guest's blood," vowing "severe punishment."
Pezeshkian also condemned the killing and pledged to "defend the country's territorial integrity, honor and dignity."
Haniyeh's mass funeral will be held in Tehran on Thursday before his body is transferred to Doha for last rites and burial, according to Hamas.
