Spurs made their move earlier this week as they stepped up efforts to strengthen Roberto De Zerbi's midfield options ahead of the new season. However, Newcastle turned down the proposal, underlining their determination to retain one of their key players.
De Zerbi has long been an admirer of Tonali, and Tottenham have spent recent weeks exploring the financial framework required to complete a deal for the 26-year-old.
Despite the setback, Spurs remain hopeful that an agreement could still be reached.
It is understood that the North London club are now weighing up a revised proposal that would move closer to Newcastle's valuation, potentially through a package heavily structured around performance-related add-ons.
Newcastle are believed to value Tonali at closer to £100m and are in a strong negotiating position, particularly with rival Premier League clubs keeping a close eye on developments.
Manchester City and Arsenal are both understood to be monitoring the situation, while Manchester United have also expressed an interest in the midfielder. However, United are not currently expected to make a formal move. AC Milan have also shown real interest.
Tottenham's recruitment team are simultaneously assessing alternative options should negotiations fail to progress. Crystal Palace midfielder Adam Wharton remains among the players under consideration, with Spurs known admirers of the England international.
The coming days are expected to be crucial in determining whether Tottenham can make a breakthrough in talks for Tonali.
Spurs remain optimistic that a deal can be struck, but they are also prepared to move on to other targets if there is no indication that Newcastle's stance is softening.
Tonali has established himself as a central figure, and Newcastle's reluctance to sell means Tottenham will likely need to present a significantly improved package if they are to have any chance of securing one of De Zerbi's priority transfer targets this summer.