The penalty means that Alpine's Esteban Ocon moves up to third and Ferrari's Carlos Sainz will start fourth. Mercedes' seven-time World Champion Lewis Hamilton will start fifth.
"Norris was on a fast lap and caught Leclerc in the middle of the tunnel and was clearly impeded," stewards said in a statement.
"Both drivers agreed that there was little that Leclerc could have safely done in the tunnel to avoid impeding Norris, given the difficulty in vision" they added.
"In fact, the Stewards observed that Leclerc reacted in a sensible way to a blue flag displayed by the marshals, but at this point, it was too late."
The stewards said, however, that Ferrari had not warned Leclerc about Norris' approach until the Briton was already directly behind.
"The Stewards believe that there is much that Leclerc could have done prior to the tunnel to avoid the impeding had he received warning from the team at an appropriate time," they added.
"Thus, the Stewards consider that the impeding was unnecessary."
