Tottenham were held 0-0 by Everton at home, extending their wait for a Premier League goal to four matches, one of the longest such droughts in the club's history.
Robertson, speaking to Sky Sport, said Tottenham needed to keep faith in their performances despite the continued lack of a cutting edge in front of goal.
"It's about staying positive," Robertson said. "Continue like this and keep working hard every week. Today, for most of the match, I think we played really well. But we're missing the key element. Matches are won by scoring goals. We have the quality, but at the moment we're not showing it."
The defender pointed to a spell in the first half when Tottenham were reduced to ten men as a turning point in an otherwise encouraging performance.
"The only setback in the first half was when we were down to ten men for a while," he said. "We mustn't let things like that affect us. There was a change of rhythm in the first half, but then we got back into the game. I never felt Everton were in control.
"Our final decisions in the last third need to be much better. We mustn't rush, stop watching the clock, and we mustn't panic. There's a lot to take from today that's positive, but there's also a lot of work to do."
Robertson, who joined Tottenham as a free agent from Liverpool over the summer, also highlighted defensive progress after a difficult start to the season at the back.
"We conceded five goals in the first two games, but now we've kept two clean sheets," he said. "It takes a lot of courage to do that. We need to put all the pieces of the puzzle together. It's not through lack of effort. If you can't win, at least don't get beaten."
Asked about the crowd's reaction at the final whistle, the Scotland international was understanding of the frustration inside the stadium.
"They were excellent in the first half and put us under pressure," Robertson said. "Unfortunately, it's natural, given the difficult couple of years this club has been through. These fans have walked through these gates too many times without ever seeing their team win. We have to change that together.
"We have to stick together and fight together. In the end we were all frustrated because I thought we should have won the game, given the chances we had. Fans come to the stadium wanting to be entertained, and today we didn't give them that. So there's no problem if they show their frustration."