Originally Posted by cyberxxx

Not exactly. That can be considered as an act ow war only in case if it was invaded by the government military forces. For example, like Russian army attacked Georgia (independent country) in 2008 (so-called 5-day war).

The British embassy was attacked by students. In fact the Iranian police was trying to stop them. So it's just a rude and barbarian act, but not an act of war.