The 17-year-olds both signed new contracts at Tannadice last month, but continue to be linked with January moves away from the club.
Midfielder Gauld is reportedly on the wanted list of Arsenal, Liverpool, Manchester United, Real Madrid and Roma, while defender Souttar is rumoured to be a target for Everton and Sunderland.
However, McNamara believes the teenagers' performances this season have demonstrated that the gossip is having no impact on their form.
"It just becomes normal for the lads," said McNamara in the Daily Record. "As a youngster you put it to one side and concentrate on what is happening on the pitch.
"It shouldn't affect them and, to be honest, you can see in their performances that it isn't."
United winger Gary Mackay-Steven has been impressed by the youngsters and is hopeful that his team-mates will not leave in the New Year.
Mackay-Steven said in The Courier: "These are exciting times for us. The manager has confidence in the young boys and if you are good enough then you are old enough.
"The young lads are making great leaps in the first team. They are just level-headed boys who are happy to play football and it's like being in the playground at training. It's great for them and they all have bright futures.
"However, from a selfish point of view I hope everyone stays in January, definitely, because I feel we can achieve something here."