Horner said it was “unfair” to boo Vettel, who has suffered repeated ill-treatment this year and was again subjected to loud chants and heckles after winning the Singapore GP.
“There is a small collective group and it is like a pantomime, but it is so unfair because it is not sporting,” said Horner, according to Autosport.com.
“The boy today has driven an unbelievable race, and I just don’t think it is sporting to see a driver, who has put a performance in like that not get the reception he deserves.”
Booing erupted after Vettel’s wins in Belgium and Italy, and surprisingly at the less partisan circuit of Singapore, as Vettel moved closer to a fourth straight world title.
The opprobrium has been put down to plain boredom from fans, as the German has won more than half the races this season and already has one hand on the championship trophy.
Vettel led from pole to the chequered flag in a super demonstration of uncatchable front-running.