The Dons will play either Ordabasy Shymkent, who finished fourth of in the Kazakhstan Premier League last season, or seventh-placed Bosnian side NK Siroki Brijeg.
They will be seeded in every qualifying round they play. Champions League play-off losers automatically make it to the Europa League group stage like Skenderbeu did in the 2015-16 campaign.
League of Ireland side Derry City will face FC Midtjylland (Denmark), who beat Manchester United past year, while Shamrock Rovers take on Stjarnan (Iceland) and Cork City come up against Levadia Tallinn (Estonia).
Ward celebrates big win while Kovalev plans protest
Rigondeaux and Flores were trading punches when the bell rang to end the first round and both threw after the bell. Nevada boxing officials huddled for several minutes and watched the replay before ruling the punch was legal.
Welsh trio Bala Town, Connah's Quay Nomads and Bangor City will also be fighting it out in the first round, while Aberdeen will learn which of two first-round teams they will take on in the second round.
The first leg is scheduled to take place on 29 June with the return on 6 July.
If Pedro Caixinha's men progress to the second qualifying round then they will face the winners of the tie between Cypriot outfit AEL Limassol and St Joseph's of Gibraltar.