Arsenal will travel to Norway, Netherlands, and Switzerland in their group games.
Manchester United will come up against Neil Lennon's Omonia Nicosia in the group stages of the Europa League.
They've been paired together in Group E, alongside Real Socidead and Sheriff.
Arsenal find themselves in Group A with PSV, Bodo/Glimt and Zurich.
Ferencvaros - who qualified thanks to a play-off win over Shamrock Rovers - are with Red Star, Monaco and Trabzonspor in Group H.