United were close to City a month ago but, since then, have drifted away.
Guardiola’s side have won their last 18 matches across all competitions and, now, are the favourites to win the title.
But Solskjaer has shut down theories the title race is already over, insisting United will do all they can to win the prize.
“I am never going to say it’s done until it’s done,” he said.
“We have seen so many examples of teams that have hung in there, have kept working and have kept doing their own jobs.
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United took the lead against Newcastle through Marcus Rashford.
And, though Allan Saint-Maximin levelled, they ended up winning courtesy of goals from Daniel James and Bruno Fernandes.
James has improved of late and Solskjaer was delighted for the Wales international after the match.
“He never disappeared. He has been working hard behind the scenes and always been available,” said the 47-year-old.
“He is always a player you can use in different areas with his energy and pace.
“We work with him, we try to help everyone but of course Dan came from the Championship, he hit a few goals in the first games and it is bound to take some energy from you.
“He has knuckled down and really worked to get back to full fitness but maybe more so confidence, to believe in himself.”
Meanwhile, Newcastle boss Steve Bruce has insisted his side will avoid relegation – despite falling to an eighth defeat in 10 games.
“Fulham have had a good week and won a couple of games, which at the bottom end of the table is big,” Bruce said.
“My message to the supporters is that I’m convinced we’ll be OK.”
Bruce also insisted he was happy with his side’s performance, adding: “I agree with you, it’s gloomy, but I was pleased with the performance today, especially in the first hour.
“But you have to turn those performances into results and I’m still quietly confident we will get the results we need.
“Of course fans don’t want to see their team at the wrong end of the table, I understand that totally.
“We have a unique fan base which makes us the club we have got, and of course they are anxious.”
Solskjaer’s side are next in action against Real Sociedad on Thursday.