Nasrallah's death nearly five months ago in a huge Israeli strike on Beirut's southern suburbs left Hezbollah supporters in disbelief and sent shockwaves across Lebanon and the region.
Norway-based Iran Human Rights (IHR) and French group Together Against the Death Penalty (ECPM) said the figure was the highest since IHR began recording executions in Iran in 2008.
US President Donald Trump's forceful backing of ally Israel has put the ceasefire under strain, and particularly his proposal to take over the Gaza Strip and remove its Palestinian inhabitants.
After the ceasefire came into force, Trump touted a plan to "clean out" the Gaza Strip, reiterating the idea on Monday as he called for Palestinians to move to "safer" locations such as Egypt or Jordan.
Israel had been preventing vast crowds of Palestinians from using a coastal road to return to northern Gaza, accusing Hamas of violating the truce agreement by failing to release civilian women hostages.
