Remy Cabella, Sammy Ameobi and Yoan Gouffran each pounced on ponderous home defending to secure John Carver's first win since replacing Alan Pardew in the Newcastle hot-seat permanently earlier this month.
Hull thought they had earned an equaliser in first-half stoppage time when Elmohamady turned Gaston Ramirez's free-kick home with his hand.
However, after furious Newcastle protests and consulting with his assistants, referee Phil Dowd promptly booked the wing-back.
Bruce said: "We're struggling at the moment, but thankfully the linesman and the referee got it right. For however much we're struggling, certainly we don't want to be seeing goals scored like that. I think it's a reaction rather than cheating.
"We've all done it as players - stick your arm up and get a touch on it. Fair play to the fourth official, I think played the biggest part in it, because I don't think the linesman gave it and I don't think the referee did. Fair play to the fourth official, he stepped in and made the right decision."
Hull have now lost three consecutive games without scoring a goal and remain in the Premier League relegation zone, leaving Bruce exasperated at his side's recent efforts.
He said: "Unfortunately for me it fizzled out to too drastically and for however good we were in the first half in particular - the same thing happened at West Ham, we were good last week - but we have to simply stop gifting people goals like we have done again today.
"Just before half-time we've made a mistake which they scored from. Up until then I thought we were the better team.
"The second half we have made a catalogue of errors for the second goal. And the one thing you need after that is for them to show a bit of resilience and a bit more determination to try and rectify the situation.
"If we're going to be honest, after the second goal went in it turned into of those horrible afternoons that we could all do without."
