The committee also refused to set a minimum age for cycling on the country's roads.
Both recommendations were part of Via Secura, a package of 36 measures aimed at reducing the number of road deaths by 25 percent.
Presented by the Swiss cabinet in October 2010, the package was approved by the Senate in June, with small modifications, and was expected to receive the endorsement of the National Council.
But on Tuesday, the Transportation Committee said ‘no’ to the new rules on young cyclists, newspaper Il Corriere del Ticino reported.
The committee said that helmets should continue to be voluntary for all riders, regardless of their age, although it did recommend the use of head protection. The proposal was defeated by 18 votes. Only four national councillors voted in favour, and two abstained.
The Transportation Committee also voted against setting a minimum age for riding a bike, arguing that parents bear responsibility for assessing the riding ability of their children.
The Federal Council had proposed that no child under seven be allowed to ride a bicycle on Swiss roads. The Senate meanwhile had voted in favour of a lighter version whereby no child under six could ride a bike on a busy road if unaccompanied, but both proposals were defeated.