(VOVworld)- Iranians held mass protests on Friday across the Islamic Republic, angered by Saudi Arabia's execution of a Shiite cleric that has enflamed regional tensions between the Mideast rivals.

A Shia Muslim who lives in Greece takes part in a rally against the execution of cleric Sheikh Nimr al-Nimr, outside Saudi Arabia's Embassy in Athens, Wednesday, Jan. 6, 2016.

Later in the day, the Iranian foreign minister insisted in a letter to the U.N. chief that Tehran has no desire to escalate tensions and said Saudis must make a "crucial choice" — either continue supporting extremists and promoting sectarian hatred or promote good neighborliness and regional stability. The crisis has seen Saudi Arabia sever ties with Iran after crowds of protesters in Iran attacked two of its diplomatic posts on Sunday. Those assaults came after Saudi Arabia executed Sheikh Nimr al-Nimr, a prominent opposition Shiite cleric, the day before.