The romantic drama stars Ranbir Kapoor, Anushka Sharma, Aishwarya Rai Bachchan and Fawad Khan.
The 44-year-old director took to Twitter to make the announcement.
"The #AeDilHaiMushkil teaser will be out on the 30th of August....My 6th directorial feature....@DharmaMovies @FoxStarIndia," Karan wrote.
"Queen" actress Lisa Haydon also has a cameo in the movie, primarily shot in London.
"Ae Dil Hai Mushkil" is scheduled to release on October 28.