Deployed as the lone marksman, Nish endured a frustrating afternoon as the hosts failed to create any clear-cut chances. And a section of fans jeered as he was replaced in the 70th minute by defender David Stephens.
He said: "The fans always have to support the team, we are trying to work hard on the pitch. When things are not going well we definitely need the supporters.
"Colin always tries his best and does all he can and I think the fans always have to support us. He is a smart guy, he knows this happens in football and if he scores twice next week then he is the hero, that happens in football.
"We have told him not to worry about it, that we support him in the dressing room. It was difficult for him against St Johnstone because they play with a lot of people behind the ball and he is the only one up front. He was up against two strong defenders and there were long balls going up to him, you try to help him but he was a bit unlucky."