The Bayern Munich president has revealed the pair have had their issues in light of the impending arrival of the former Barcelona boss.
Heynckes, who left Bayern Munich for Bayer Leverkusen in 2009, was reinstalled at the Allianz Arena helm in 2011 in a bid to halt the charge of Borussia Dortmund.
Since then, the 67-year-old has successfully wrestled the Bundesliga title from BVB's grasp this season and reached the semifinals of the Champions League, as well as the final of the DFB-Pokal.
However, Hoeness' decision to reveal Guardiola would replace Heynckes at the end of the campaign led to a souring of relations between the club president and current coach.
The 61-year-old told Sport: “I admit, there was some tension between Jupp and I. But that has completely returned to normal. Jupp and I are friends and we'll stay that way."
Bayern has become the fastest team to secure the league title in the history of the Bundesliga, and Hoeness believes it must thank rival Dortmund, which has forced Bayern to improve.
"We are grateful to Dortmund. They have really challenged us and thus led to another level. Thanks to BVB we have become so strong. Dortmund is not a fluke. They will be a permanent adversary."