Social Security is paid to Americans who qualify, as long as a U.S. Income Tax Return is filed yearly.  There is no accommodation at this time for funds to be placed into a Croatian bank account.  

The Federal Benefits Unit has an office in Croatia.  Contact information follows:

American Embassy
Thomas Jefferson 2
Andrije Hebranga 2
10000 Zagreb
Croatia

Email:   FBU.Zagreb@ssa.gov

The FBU link follows:
http://www.ssa.gov/foreign/foreign.htm