The 27-year-old scored his 40th league goal of the season as he bagged a hat-trick at the Estadio Vicente Calderon.
"There is a lot left, but winning La Liga has got closer now," Ronaldo told reporters. "There was pressure on us because we knew Barcelona had won their match. We are still four points clear.
"We knew this was going to be a tough match, but we gave a good account of ourselves against a very strong Atletico side."
Los Blancos continue their campaign on Saturday when they host Sporting Gijon.