United, hoping to exert even more pressure on second-placed Manchester City before they hosted Liverpool on Sunday, laboured at times but Rooney's 79th-minute strike proved decisive.
"It was a fantastic, battling performance. There was a great determination about us. I thought they were really up for it, the players, making sure they weren't going to lose the game," Ferguson told United's website.
Both sides struck the woodwork in the first half, Patrice Evra for United and Brian Ruiz for a lively Fulham side while Rooney also thumped a shot against the post in the second half before capitalising on an error to make the breakthrough.
Philippe Senderos, whose misjudgement allowed Rooney to race on to a long ball and score, nearly equalised in stoppage time with a header that was cleared off the line by the Premier League's top scorer Robin van Persie.
United, who now have 62 points from 25 games with champions City on 52, are setting a relentless pace at the top although Saturday's win and the one in midweek against Southampton owed as much to grit as style.
Ferguson said coming away with three points from Craven Cottage had been hugely significant.
"They've had a great home record over the years and that's a really important result for us. It's a good position [being 10 points clear], we're pleased," said the Scot.
"This is not an easy place to come to, as everyone knows, and over the years they've been difficult to beat here. It's a good performance, a really good game, an important result."
United had lost two and drawn one of their last four league visits to Fulham and the London club can count themselves a little unlucky at failing to take points off the leaders.
"When you look at our performance, you saw players who were prepared to put their body on the line," Ferguson said.
"We blocked shots, had great headers out of the defence, it was a really determined effort by the players and we still played our football into the bargain."
