The Egypt international scored 44 times in his maiden season at the club but has not looked close to replicating that form this time around.
He has scored three goals so far, only one fewer than at the same stage 12 months ago when he did not really begin his scoring spree until this time of the season.
Wijnaldum said they had been teasing Salah about his supposed struggles, jokingly telling him he has to score more.
“I said ‘Mo, it’s not only one year’ and he said ‘you’re right!’,” he said, ahead of the Champions League tie against Napoli in Italy.
“We were joking but if someone can deal with pressure, it is Mo.
“Last season he had pressure when people were saying he had to be the top scorer of the league.
“We told him he couldn’t let anyone catch him. When he was on 18 goals, he said ‘in my head, I can get 32’.
“Mo is not someone that is scared of pressure. He embraces the pressure. He knows that he can do it.”
Klopp has already said no-one at the club expects Salah to reproduce his amazing form this season and Wijnaldum says the players all support him.
The Dutchman said the forward had contributed more to the season than just goals.
“It’s easy to say ‘now we have Mo, we are used to him scoring goals’,” he added.
“Maybe last season he didn’t have some good games but he always scored goals and people see that and they say ‘ah! He played good!’.
“But now he is not scoring and people are saying he is in a difficult situation. I don’t see it that way.
“He still works hard, he still creates chances. I think against Chelsea, he had three chances where he could score a goal. He could have given an assist to Roberto.
“I don’t think it’s that bad, put it that way.
“I’ve told him that he’s got to get more hat-tricks. He’s had enough of scoring twos, he has to get three.
“I told him ‘Mo, you are a top player; if you look at Messi and Ronaldo, they score a lot of hat-tricks—you have to do the same if you want to compete with them’.”