The coach is keen to add to his squad in the market next month but stressed that the club will only look to make signings who can make an impact on the team for "four or five years".
Guardiola said: "The transfer window in the winter is not easy. Even the players know that we have to add some new players. But after, when these players come and play in their positions then they are unhappy.
"But we have a lot [of injuries] and this is a problem. It's about bringing a player for the next four or five years and we'll have to see. Sometimes it is not easy. We have to try because this is sustained for a long time."
City's terrible run of form continued as they were held to a 1-1 draw by Everton in the Premier League on Boxing Day (26.12.24) and Guardiola had no complaints about a result that means his team have won only once in their past 13 games.
He said: "I think we were very patient. That is the momentum of the season, that is a little bit of the situation.
"Everything takes more time to make it work. With the table, I have no argument. Football is about winning, scoring goals and not conceding, and we've always done it until the last month and a half. We're not able to do it."
Erling Haaland missed a penalty for City but Guardiola refused to blame the misfiring striker for the disappointing result.
He said: "Life is not easy, sport is not easy. When that (penalty save) happens, it’s OK."