Dortmund, champions in 2011 and 2012, have been languishing in the bottom spots of the Bundesliga table and lost 10 of their 17 matches in the first half of the season.
"We will never sack Juergen Klopp," Watzke told SportBild magazine. "He has a lot of merits at the club. It will never come to a confrontational situation with him."
Klopp, who took over in 2008 and also led them to the 2013 Champions League final, has suffered his worst first half to a season at Dortmund, Bundesliga runners-up in 2014.
The coach has already reacted, signing Slovenian Kevin Kampl from Red Bull Salzburg to boost his midfield in a reported 12-million euro deal. The league resumes on Jan. 30.
Despite their bad domestic run Dortmund are still in the running for the Champions League title, taking on Juventus in the round of 16 next month.
(Reporting by Karolos Grohmann, editing by Alan Baldwin)
