Josh Rutledge doubled twice and scored once, while Charlie Blackmon added two hits and drove in a run for the Rockies, who avoided a sweep and put an end to their seven-game losing streak.
Nolan Arenado, Ben Paulsen and Michael McKenry also knocked in a run each, to back the performance of Jorge De La Rosa (11-6), who fanned a season-high 11 batters while permitting one earned run and eight hits over 7 1/3 innings.
LaTroy Hawkins made it interesting in the ninth, allowing run-scoring hits from Jayson Werth and Anthony Rendon. A fielding error by Rutledge on a routine grounder from Adam LaRoche loaded the bases, but Ian Desmond fanned swinging on a 2-2 pitch to end the rally.
Denard Span finished 4-for-5 with an RBI and crossed home twice for the Nationals, who had won four in a row. Stephen Strasburg (7-8) gave up nine hits and four runs over 5 1/3 frames, fanning five but walking three.