Four members of the Birmingham gang were jailed last week for killing Charlene Ellis and Letisha Shakespeare in a drive-by shooting on New Year's Day 2003.
On 20 March, the Sunday Mirror reported that in the video, which was filmed at February's Brit Awards in London, Jamelia says: "Big up to the Blood Brothers" - which is code for the Burger Bar Boys.
The singer then apparently uses her fingers to make the shape of a gun and adds: "Pop, pop, pop."
As an ambassador for NCH, Jamelia has appeared as a role model for young people in a high-profile campaign. However, NCH said it had no plans to review her position.
A spokeswoman said: "Jamelia's experience of some of the issues that affect the children and young people we work with - namely bullying, single parenthood and safety on the internet - has meant that her support has been very well received by our service users and the public alike.
"NCH is grateful for her contribution and, as such, has no immediate plans to review her role with the charity."
The spokeswoman added that the charity could not comment on the video because it had not seen it.
Jamelia, whose hits include Superstar and Thank You, has also done work for the anti-gun crime charity Disarm Trust. She has previously distanced herself from the Burger Bar Boys, of which her half-brother and step-brother are members.
Following the verdicts on the News Year's Day shootings, Jamelia said: "I am totally opposed to violence and horrified by the extent to which crimes involving guns have pervaded our society."
Third Sector was unable to contact the Disarm Trust.
Jamelia's other charity work includes supporting the Make Poverty History Campaign
Her half-brother Tumbi "Muscles" Beckford, 21, is serving life for shooting dead Daniel Bogle, 19
Her step-brother Tafarwa Beckford was cleared over the drive-by shootings
Her natural father, Donald Williams, has served five prison terms but was not involved in her upbringing
Last summer the singer pulled out of the Party in the Park in Birmingham after receiving death threats.