A Brooklyn councilman and another politician’s aide were detained yesterday during a heated exchange with cops after the West Indian Day Parade.

Councilman Jumaane Williams (pictured) and Kirsten John Foy, a top aide to Public Advocate Bill de Blasio, said they were walking toward a post-parade reception at the Brooklyn Museum at around 1:30 p.m. when they were stopped by cops.

Police said Williams’ entourage was walking through a “frozen zone” for emergency personnel only and were detained until their identities could be confirmed. Williams and Foy were not charged.

Police Commissioner Ray Kelly later met personally with the pair and said he was launching an investigation into the matter.

Mayor Bloomberg also spoke with Williams, his rep said.