Toto Wolff has explained why Mercedes declined Red Bull's request to supply the team with power units from next season.
Red Bull is heading towards a divorce with current partner Renault and sounded out Mercedes over a potential engine deal for 2016.
Mercedes rejected Red Bull's approach, meaning that the squad is now reliant on being powered by Ferrari from next year.
"We decided with our board that we as an engine supplier - and as a team - have worked hard and long to achieve the success we have today, after taking the decision to enter the sport again as a works team in 2010," Wolff explained to the Official F1 website.
"Therefore we decided two weeks ago against exploring an engine supply to Red Bull.
"We wish to continue with our model to support independent, privateer racing teams - and to respect the relationships we already have in place with our customers - alongside our primary focus on the Mercedes works team."
Mercedes currently supplies Williams, Lotus and Force India with power units.