Stop? No. Slow down enough for the Germans to bring in the requisite reinforcements too stop it? Sure.
It was ~70 kilometers from the Soviet start point for Uranus to Kalach. On the other hand, it's ~390 kilometers from the Soviet start point for Uranus to Rostov. It took the Soviets 4 days to link up at Kalach, a rate of advance of 17-18 kilometers a day. Even if we assume nothing else gets in the way to slow down the Soviet advance toward Rostov (like the 6th Panzer Division), it would still take almost an entire month.
Much better for the Soviets to shatter the Romanian armies, encircle the 6th Army, force the remaining Germans formations to be pinned into doomed efforts to try and relieve the 6th, build-up and reinforce, and then utilize their more forward positions to drive on towards Rostov while the 6th Army starves to death.