"Whilst this delay in the opening of Crossrail is regrettable - and the rail industry must always learn lessons on delivering major projects to deadline and budget - we should remember that schemes like Crossrail and Crossrail 2 have a transformational impact on the United Kingdom, its economy and connectivity and therefore a delay to one should not affect decisions on the other", he said.
The comments, along with previously confidential documents released by TfL, revealed the extent of the delays and financial troubles, and that government and London transport chiefs were informed of the first alert that Crossrail's schedule was in serious trouble as far back as June 2016.
TfL said the briefings being sent to Mr Khan provided a "snapshot of the status of the project".
He has accused Sir Terry of "misremembering" discussions and said he was not told of the need to change the opening date until Aug 29.
"That took out any reference to not being able to deliver the programme in 2018".
Sir Terry also reiterated that the mayor was told on 26 July that a 2018 opening was "no longer feasible".
He said: "It is also true to say that, there was a TFL board meeting on the 25 July, I just want to clarify that, it never happened before, but I was given a sheet".
Sir Terry, who resigned as chairman of Crossrail and HS2 in December after predicting he was about to be be sacked due to delays and cost overruns, told the London Assembly Transport Committee that weekly briefings were "cleared" by TfL before reaching the mayor.
Sir Terry Morgan, the former chairman of the project, said that incriminating passages from a briefing document warning that the scheme was running late had been deleted.
He pulled back the curtains on the relations between Crossrail, TfL and City Hall.
This information was shared with the mayor on July 26 and was "a very clear indication" of the delay, he told the committee.
A Mayor of London spokesperson said: 'The Mayor has been fully transparent about what he knew about the delays to Crossrail, including around the information that the previous Crossrail leadership gave to TfL and DfT as the joint sponsors.
Ms Alexander added she was struck by a "lack of realism from Sir Terry about what was really going on with this project".
He said that TfL had instructed him to omit references to a delay from a presentation being given to officials and spent nearly a month on a communications strategy to explain away the chaos to the public.