The students, aged between 12 and 14, were rushed to the Vidyasagar Institute of Mental Health and Neuro-Sciences (VIMHANS) for food poisoning but were later discharged, they said.
The 12 students of Sarvodaya School in Nehru Nagar in Lajpat Nagar complained of stomachache and nausea after eating the food served to them under the mid-day meal scheme. Some of them complained of vertigo and vomiting.
The children were kept for about three hours under observation in the hospital and then allowed to go.
A case has been registered, police said.
Meanwhile, Delhi's Education and Women and Child and Social Welfare Minister Kiran Walia has said that strict action would be taken against those found guilty.