City have gone down 1-0 away to the Central Coast Mariners and 3-2 at Western Sydney Wanderers FC in the last six days, leaving them seventh, one point behind Brisbane Roar but having played two matches more than their playoff rivals.
Next up is a home game with the Newcastle Jets on Saturday, a contest van 't Schip knows his players have to win to remain in the hunt.
"We're still confident," he said.
"We haven't made it easier. They [Brisbane] have the advantage now, they have two games in hand, they are leading by one point.
"If they don't make any mistakes, then it's easy [for them], they're in. We have to make sure we keep believing."
Van 't Schip confirmed Josh Kennedy will return to the starting XI after being rested for the defeat in Parramatta on Wednesday, while former Jet Kew Jaliens is likely to line up against his old side at centre-back in place of another Hunter Stadium old boy, Connor Chapman.
The 20-year-old will be suspended for at least one match after seeing red at Pirtek Stadium, with a Football Federation Australia disciplinary committee potentially set to extend the ban.
"Hopefully everybody has a good look at it and they will see there's not maybe that much going on," van 't Schip said of the incident.
"Then of course it's up to them to decide. Hopefully they take into consideration that Connor's track record [is good]. If not, we have to cop it.
"We had a chat. Of course he's disappointed. He's a young boy. He's important for us. This is something he'll learn a lot from."
Injured star Damien Duff this week flagged a likely return to Ireland in the coming months after his season was ended by a serious ankle and calf injury.
According to van 't Schip though, the veteran, spotted undergoing the early stages of his rehabilitation at City's gleaming new training complex on Friday, is yet to confirm he will not be staying for a second Hyundai A-League campaign.
"We talked about it but it's [at an] early stage," he said.
"Of course he's thinking about the rest of his career but also the rest of his life after football. A combination of maybe doing some courses to get his coaching badges and playing ... to finish in a good way.
"I can imagine if you have to stop like this with an injury, maybe you want to do it a different way. It's totally up to Damien. He will come up with something he's happy with."