More than a dozen members of the Free Burma Coalition carried placards reading "Free Burma Now" and "Free all political prisoners in Burma."
"We think that calling for Suu Kyis release would be the best gift that we can offer on her birthday," Gus Miclat, a spokesman for the coalition, said in a statement protesting the Myanmar governments recent decision to extend Suu Kyis house arrest for another year.
The protesters, two of them with chains around their ankles, were joined by two South Korean activists.
The demonstrators brought a giant cardboard "cake" bearing a picture of Suu Kyi and the number 61. They also attached buntings at the facade of the building housing the embassy as a handful of policemen watched.
"The juntas decision extending her house arrest can never be acceptable to the international community," Miclat said.
Suu Kyi, the 1991 Nobel Peace Prize laureate and one of the worlds most prominent political prisoners, has spent 10 of the last 17 years in confinement.
Myanmars ruling military junta took power in 1988 after crushing massive pro-democracy demonstrations in Myanmar, formerly known as Burma. In 1990, it refused to hand over power when Suu Kyis party won a general election by a landslide. AP