Obama is against Hamas because Hamas is an obstacle to Israeli national suicide. Obama wants to get tiny Israel to retreat to the suicidal pre-1967 borders. And Obama wants to be the president who created the independent terrorist state of "Palestine" in Judea, Samaria, the Gaza District and Jerusalem.
If Israel went into Gaza to forcibly remove Hamas from power and to install the Fatah-PLO Nazi terrorists in their place, Obama and the Jew-hating European Union would support such a move.