These actions are done so that newer generations would never forget what the west did to them. The west stole Iranian money for decades, killed Iranians, and destroyed their land. This thing is still going on around the world against muslims in general and not just Iranians, and such acts should be stopped. When we chant such things, we dont really want to kill the americans, we are protesting against the american government. We dont want such terrorists killing and stealing from the muslim world. Look at what's going on in Yemen. Children are being killed like they are flies. Saudis perform strike missions daily, reaching up to 200 strike missions per week. Why should all this happen around the world. Next time you see someone chanting death to america, death to israel and burning their flags, remember the Yemeni and Palestinian children and civilians, remember what happened to Iraq and Syria, remember what happened to Iran before the revolution, and you will see that such actions are justified. Why do you think it's the Iranians who should behave themselves, look at all the terrorist acts done by the west.