Vettel, the two-time world champion, labelled the Indian “stupid” and accused him of costing him points as the action at Sepang reached its exciting climax.
Karthikeyan, who is India’s first Formula One driver and races for the struggling HRT team, later branded the German “a cry baby”.
“It’s always a shame to lose points, but these things happen,” Vettel said in Shanghai ahead of the Chinese Grand Prix, adding that he had no regrets.
“We need to move forward. It’s a racing incident. I’ve spoken to Narain and there’s nothing more to say.”