Bob Crow, leader of the RMT union, said: "It does Londoners no favours to be told by London Underground that stations will be open, only to turn up and find the gates slammed shut."
Mr Crow and Manuel Cortes, leader of the TSSA union, accused Mr Johnson of refusing to meet them to discuss the ticket office closures.
But Mr Johnson continued to attack the strike, insisting LU was planning to increase staffing levels through modernising the Tube and getting rid of "antiquated" ticket offices.
"A deal is there to be done. I am more than happy to talk to Bob Crow if he calls off the pointless and unnecessary strike."
Members of the RMT and TSSA unions walked out at 9pm last night for 48 hours in protest at the closure of all ticket offices, with the loss of 950 jobs.
Services are due to return to normal on Friday but another 48-hour strike is planned from 9pm next Tuesday.
Business groups warned the strikes will cost London's economy tens of millions of pounds.