Several foreign diplomats wrote their thoughts in a book of condolences.
"The start of 60% enrichment in Natanz was a demonstration of our technical ability," Iranian government spokesman Ali Rabiei said.
The negotiations in Vienna are for the Iran to scale back its enrichment from 60%
On the agenda for the foreign ministers’ meetings are economic issues, security, tourism, battling coronavirus and establishing a “green corridor” for travel between the countries.
Israel has until April 9 to respond to an ICC letter it received last month informing it that a war crimes investigation had been opened.
Later on Friday, President Joe Biden announced that the US would be lifting its sanctions on the International Criminal Court, which were announced during the Trump administration.
A Bahraini team is expected to arrive in Israel in the coming weeks to set up an embassy in the Tel Aviv area.
Ashkenazi flies to Moscow after Lavrov-Hezbollah meeting
On the security side, the situation is said to be better and the militaries in both countries are believed to regularly work together against common threats.
"It is necessary to resume serious and effective negotiations to achieve a just and comprehensive peace based on the two-state solution."