Yes. Check the FCOM part 3 - Abnormal and Emergency Procedures - After Eng1(2) Shutdown checklist.
If you have pushed a Fire PB you should SHUT the X-Bleed in order to prevent cross-contamination of bleed air by fuel/hydraulic oil/engine oil/extinguishant from a damaged engine. That's why you should avoid icing conditions after an engine shut-down; you cannot use Wing Anti-Ice - you'd need the X-Bleed OPEN for it to protect both wings.
If you have pushed Eng 2 Fire PB you may use the APU bleed AFTER you have SHUT the X-Bleed because by doing so you can isolate Eng 2 bleed. If you have pushed Eng 1 Fire PB you may not use APU bleed at all because you cannot isolate Eng 1 bleed - both Eng 1 bleed and APU bleed are on the same side of the X-bleed.
Hope that helps.
WS