United, who scored 89 goals in the league last season, have only managed to notch up three in their first four pre-season games.
In Oslo, United drew 0-0 with Valerenga on Sunday but the Reds' returning skipper Vidic is adamant this is no cause for concern.
"When you see the kind of chances we’re creating it’s a relief," he told ManUtd.com. "I know we haven’t scored many goals so far but it will come.
"We’re not clinical in front of goal yet but we have the next few games to work on that and fix that. I’m not really worried about it.
"If you look at the team that played on Sunday I think we had about five or six players who were playing their first game after almost two months.
"Some played almost 90 minutes and to do that after nearly two months off is a difficult ask, especially when we played against a team that has 15 games already in their legs.
"But I think a lot of guys have returned from their summer break a lot fitter than usual. You can see it in their body language and this is a positive sign.
"We had some chances in Oslo and we didn’t score but, overall, we got what we wanted out of the game, physically."