The Hungarian, who played for Greek club Asteras Tripoli last season, is undergoing post-operative treatment, reports BBC Sport.
"I am sure that after a few months I will be ready both physically and mentally to continue playing football," the 30-year-old said in a statement.
"I'd like to train between treatment courses, as the doctors have said this is fine and heartily recommend it."
"My contract in Greece has come to an end and with a successful season behind me there were some great career opportunities put in front of me," added Fulop, who has won 24 caps for Hungary.
"For the time being I cannot dwell on these, and I wouldn't want to put a club's management in such an awkward situation that they have to deal with my problem."