One of T-14 Armata tanks suddenly stopped on Red Square, and the driver raised a red flag - apparently to signal that he had problems.
A tow vehicle was brought in, but the tank later managed to drive on.
The parade announcer said the stoppage had been planned to show how to "evacuate weaponry".
This prompted laughter from the crowds who gathered to watch the rehearsal in the Russian capital, Reuters reports.
Alexei Zharich, deputy head of the Uralvagonzavod tank producing factory, later wrote on Twitter (in Russian) that the tank "was in full working order and left on its own".
He also posted a video showing the vehicle leaving Red Square.
Russia's military was responsible for the rehearsal, Mr Zharich added, and any questions should be addressed to it.
The T-14 Armata has been the most talked-about innovation in Russia's new armoury ahead of the 9 May World War Two Victory parade.
It has a remotely controlled cannon and offers additional protection to its crew, Russian military experts say.
And Russia's RT news says the Armata could "evolve into a fully robotic battle vehicle".
The experts also claim the tank is superior to the T-90 - the current mainstay of the Russian army - and also to all Western analogues.
Russia plans to bring in about 2,300 Armatas, starting in 2020.
Russia's new high-tech battle tank has ground to a halt during a rehearsal for 9 May Victory parade in Moscow, prompting speculation of a breakdown.