The outspoken Austrian made the remark just a few weeks after the pair collided in dramatic fashion on the opening lap of the British Grand Prix.
The crash, which Hamilton was adjudged to be at fault for, sent Verstappen into the barriers and left him requiring a check-up at the hospital.
The Mercedes driver, meanwhile, recovered from a 10-second time penalty to win his home race and put a serious dent into Verstappen’s then-33-point lead at the summit of the Drivers’ Standings.
And, with Hamilton once again outscoring Verstappen by a big margin in Hungary, the seven-time World Champion currently has an eight-point advantage over the Dutch ace.
Speaking to Motorsport Magazin, Dr Marko said he was unsure if the two drivers’ relationship will ever fully recover from the incident at Silverstone.
“We want to win the World title and for that you have to score as many points as possible. Max knows that, Hamilton knows that too,” the senior Red Bull advisor said.
“But something happened that cannot be undone so quickly in the relationship between these two, if it happens at all.
“But I hope both of them can keep it fair and under control.”
Continuing, Dr Marko said he believes “Max has proved this season that he is really at World Championship level.
“In Bahrain, of course, we had some problems with track limits, which cost us the win, pole and fastest lap.
“The sledgehammer blow in Baku, when he was leading masterfully and lost his victory because of that blowout, that’s a shame.
“But his whole attitude and relaxed way of approaching racing shows he has taken another step towards the top,” he added.