A spokesman from the US Embassy in Yangon said officials were trying to find
out details of the arrest and the man involved.
"The embassy has not yet been informed by authorities and we don't know anything about it," Richard Mei told the Associated Press.
Aung San Suu Kyi has been held under house arrest for more than 13 of the past 19 years.
She is not allowed visitors apart from her doctor and has not been seen in public for many months.
Aung San Suu Kyi's party, the National League for Democracy, won a landslide victory in 1990 national elections but the result of was ignored by Myanmar's military government which retains an iron grip on the country.