Get ready for the final moments of the campaign. I have to warn you about something. You won't be able to make any new savegames, so you have to be very careful. Otherwise you'd have to repeat this whole section. Start moving towards the destroyed embassy (#2). That's where the terrorists have barricaded themselves.
You will come across a first group of enemy soldiers in just a few seconds. The terrorists are standing just around the corner (#1). I would recommend that you aim at their heads. You MUST be VERY careful. There are two stationery machine gun posts on your right (#2). You've got two options. You can either try and take them out from a distance (lean out) or you can ask the rest of the team for help in order to be able to attack the gunners from the flank. Make sure that both soldiers are dead. If you have a rocket launcher with you, aim it at the nearby truck. Thanks to that, you'll eliminate a few soldiers (you wouldn't need the missile anymore).
Order the rest of the team to get here. Start moving towards a designated area (#1). Once you're there, wait for the final objective to pop up on the screen. Be careful, though. More terrorists will arrive in this area very soon.