How do I get past spec ops mission 2?

You should have the option to call in a Mortar Strike. Press right on the d-pad, or touch the button on screen. It'll bring up the map with the MIG icons in red. Tap those icons to place the strike. It may take more than one attempt but that should take care of it for you. Also make sure you clear out that balcony and stay inside the building when calling in the strikes. The enemies on the ground level can still kill you if you are on the balcony.