LONDON (Reuters) - A top aide to Iran s Supreme Leader warned the United States on Tuesday against designating the elite Revolutionary Guards as a terrorist group, saying Tehran has  all options on table , news agency ISNA reported.   The Americans are supporting Daesh (Islamic State). That s why they are angry with the Revolutionary Guards. But they are too small to be able to harm the Revolutionary Guards,  Ali Akbar Velayati, the top adviser to Iran s Supreme Leader Ayatollah Ali Khamenei, was quoted as saying by ISNA.  Whatever they do we will take reciprocal measures. We have all options on the table,  he added. 