The new Blues boss remained coy over further acquisitions, with unsettled Manchester United striker Wayne Rooney linked with a move to Stamford Bridge this summer
Mourinho has already brought in Kevin De Bruyne, Marco van Ginkel and Andre Schurrle as well as Mark Schwarzer to add competition for Petr Cech.
And the returning Chelsea manager remained tight-lipped on potential transfers but would not rule out spending more money in his bid to transform the Blues into title challengers.
"Big clubs will always be connected with big players, but there are always rumours," Mourinho told reporters at a press conference on Tuesday ahead of the Blues' friendly against the Singha All Stars on Wednesday.
"Until 31 August we will see if someone can improve the squad but my focus is to improve these guys.
"We want to be there [at the top of the table] and will be fighting [for the title]."