Johnson said: “Believe me, no-one wants me to find my best form more than me, and I was aware of what I had to do.
“It was a little reminder from the boss, he told me that was what he meant by it.
“We spoke, and he explained he wanted it to help me, to push me and I said to him then, I don't need people to tell me, I know where I'm at in terms of form, and I knew it all already.
“The gaffer told me he has faith in my ability, we spoke and we cleared things up. Sometimes comments like that can be made to look more negative than they are meant.
“The boss explained that he didn't mean it in a negative way, just that he knew I had more to offer than I was showing, and wanted to get that from me.â€
“No player wants to be injured, and it has been frustrating to me, to be out for so long,†he said.
“But that was more like it for me on Saturday. I think it has been a difficult season for me, but it has been a difficult season for a lot of teams and a lot of players.
“You just have to keep doing what you've done in the past, and try to reignite some of that form.
“The last seven games I haven't played, and it is impossible to improve your form if you are not out there, so it's been extra frustrating for me.
“I had some niggling injuries at the start of the season, and when you don't have that consistency it can affect your form. I'm not making excuses, but sometimes it is difficult.â€
Liverpool's win moved them to within three points of the European qualification places, despite having lost five of their 13 Premier League games this season.
And Johnson added: “It surprises me to be honest, that the win against West Ham took us to within three points of fourth place. Considering some of the points we have dropped, some of the games we have lost you'd have thought we would be out of it already, to be honest.
“But we're in there, because everyone's beating everyone at the moment and the league's really open. That means if we can put a run together we can get up there where we aim to be, and who knows, maybe we've overcome our worse spell and can push on from here.
“Every team has been dropping points where you wouldn't expect them to. That shows how good this league is and how competitive it is, but it has given us a chance to still challenge, despite some of our results. We are still quite close to the top and if we can build on this performance then I'm sure we can be close to wherewe want to be.â€