The incident happened on the Chicago-bound flight from Hyderabad via New Delhi.
A passenger tweeted about it along with a picture of the meals having a dead cockroach, following which Air India apologised for the inconvenience.
When contacted, the airline's senior manager for corporate communications Dhananjay Kumar said, "Air India took serious note of the incident and issued a notice to the caterer concerned immediately. Further investigation is going on."
Earlier in the day, one Rahul Raghuvanshi tweeted the photo and said, "@airindiain now serves cockroach for vegetarian meals on AI127 #sicktomystomach #traumatised #cockroachinfood".
In response, Air India tendered apologies for any inconvenience caused. "We have a zero tolerance policy in this respect. Obligatory action is taking place," the airline said in a tweet.