DUBAI, United Arab Emirates — Iranians began voting Friday in a runoff election to replace the late President Ebrahim Raisi, killed in a helicopter crash last month, as public apathy has become pervasive in the Islamic Republic after years of economic troubles, mass protests and tensions in the Middle East.

Voters face a choice between the hard-line former nuclear negotiator Saeed Jalili and Masoud Pezeshkian, a heart surgeon and longtime parliament member who has allied himself with…