More than 200 people have been injured, Iranian state TV has reported.
"We will not lament his death": PM makes first statement after killing of general Qassem Soleimani sparks fears of war.
The 2015 pact unravels after Qassem Soleimani was killed on Friday.
Tens-of-thousands of people filled the streets for the grand funeral procession.
The resolution was passed following the Trump-authorised killing of Iranian general Qassem Soleimani.
Foreign secretary says he and Boris Johnson have been in "constant contact" amid fears war could break out in Middle East.
The US president threatened to hit dozens of culturally and historically significant Iranian sites if the country sought revenge for the killing of Qassem Soleimani.
Thousands marched through Baghdad on Saturday for Iran’s top general, who was killed in a US airstrike.
The government has changed its advice amid escalating tensions in the wake of Trump's assisination of Iranian general Soleimani.
Demonstrators chanted "death to America" while some burnt US and Israeli flags after assassination of top military commander.