The Conspiracy Cells of Fire group is urging anarchists to "spoil the party ... And sabotage" the Nov 15-16 visit to Athens.
The nihilist group has organised a string of bomb attacks on judges, police and other authority figures. The attacks have caused minor injuries, but no fatalities.
In a posting on a left-wing website today, the group called on anarchists to use Obama's visit to "return a little of the violence we receive daily."
Anarchist groups are planning a protest march to the US embassy in Athens on Nov 15. Similar protests during a 1999 visit by then-president Bill Clinton led to extensive violence.