The pair made contact as seven-times world champion Hamilton came up behind his fellow-Briton at Barcelona's Circuit de Catalunya.
"George just backed off," said Hamilton over the radio. "That's really dangerous."
Russell failed to make the final top 10 shootout, qualifying 12th, while Hamilton needed a new front wing before the decisive session in which he was fifth fastest.
"It was just massive miscommunication," said Russell. "We need to talk internally on how that happened because, between two team-mates, it should never happen."
Hamilton told Sky Sports that the car had not felt massively different after the impact.
"It was just a miscommunication thing," Hamilton agreed, who was otherwise sounding a lot happier than 24 hours earlier.
On Friday he had talked about the difficulty of even getting in the top 10 with a redesigned car but on Saturday he said the difference was clear.
"Absolutely shocked...it was a real surprise to see us so far up front and competing for ultimately the front row. But we did some great work overnight with the analysis," he added.
Hamilton said he had been at the circuit until around 11pm on Friday trying to figure out where to find the missing performance.
"When I woke up this morning I was on a mission...I definitely didn't expect us to be fighting for front row. The car really came alive today from P3 (final practice) and ultimately just our whole package.
"Its showing that we are progressing, which I am so grateful to see, and I really enjoyed driving the car today. I was basically front row all the way until turn 10. I got into turn 10, got on the power and the car just snapped into oversteer."
Hamilton said he had lost two tenths there but was not "killer disappointed".
"Maybe if I was fighting for a world championship I would be but I'm more just really encouraged to see the car where it is and hopefully tomorrow I can progress forwards."
Red Bull have won every race so far this season with Mercedes currently third.
