The plans were discussed during a debate on the introduction of a negative licensing scheme for retailers.
Under the scheme, due to be enforced in 2008, retailers caught selling tobacco to minors three times in a two-year period could have their licences revoked for up to one year.
The Association of Convenience Stores (ACS) has been lobbying for a range of amendments to be made to the scheme, including tougher sanctions for proxy purchasers and teenagers who attempt to buy underage.
ACS chief executive James Lowman said: "Sanctions against retailers alone are not enough. This government must also deter young smokers from trying to buy. It's not only fair, it's the only way to challenge the attitudes of young people."
Speaking at the committee stage, justice minister David Hanson said there was scope to make it an offence to proxy purchase. However, he added that he was unconvinced about making it an offence for underage people to attempt to purchase. Such a move would criminalise them, he said.
Hanson also refused to accept the ACS' proposals to decrease the time frame for offences from two years to one, and to reduce the length of the ban to three months as is currently the case with alcohol sanctions.
He agreed that a notification process was needed to ensure that retailers were given the opportunity to improve should they be found to have failed a test purchase and said he would include the amendments at the Bill's next stage.