The two started on the front row of the grid at the Circuit de Catalunya, with triple world champion Hamilton on pole position, but collided on the opening lap while fighting for the lead and retired.
Stewards deemed it a racing incident and team boss Toto Wolff said it was caused by a number of factors with neither driver entirely to blame.
The collision, with Hamilton forced wide onto the grass and then losing control before his car skewed sideways and hit Rosberg's, ended the German's hopes of an eighth win in a row and fifth of the season.
"I don't even think about it anymore, for me it's way in the past and it surprises me that people are talking about it," Rosberg told reporters after a testing session at the same Spanish circuit on Tuesday.
"I understand it. For me, though, it's over."
Rosberg played down reports of rising tension between the Mercedes drivers, who have been rivals since their teenage years and whose relationship turned frosty during their 2014 duel for the title, and said they pushed each other all the time.
"Obviously, it didn't go well for us on Sunday, but our relationship remains as before," he said.
Rosberg leads Ferrari's Kimi Raikkonen by 39 points after five of the season's 21 races. Monaco is next up on May 29.
Hamilton has remained largely silent since Sunday, with a notable absence from the social media streams on which he is usually active.