The Human Rights Protection Party organised the rally to highlight judicial decisions it sees as flawed and against the Constitution.
The Samoa Observer reports the arrests were confirmed by Assistant Police Commissioner Auapa'au Logoitino Filipo who also said more arrests will be made as investigations continue.
He said the investigation is also looking at another roadblock at Sasina village and arrests are likely from there.
The arrested pair are facing charges for disorderly conduct in public places.
