More than 20 infringement notices have been issued to local stores in the Manawatu and Wanganui region since 2012.
These were for $500 while the latest two notices include a maximum penalty of $1000.
The Wellington region has also seen an increase in these sales prompting medical officer of health Stephen Palmer to ask for additional resources supporting compliance.
"It is extremely disappointing tobacco retailers continue to sell to under age people. Furthermore, the best way forward would be to introduce licences for tobacco retailers."
He said licensing would reduce the total number of retailers and allow the removal of cigarettes from those who repeatedly sold tobacco to minors.
Those caught in the latest operation have been put on "notice" and told they will be publicly named if they continue to sell to those under age.
MidCentral co-ordinator health regulation Tui Shadbolt said smoking was a significant health issue for young people.
"The sale of tobacco in our communities is a growing concern. Preventing the uptake of smoking by minors is an important focus in achieving a smokefree Aotearoa by 2025."