IndiGo has already been operating four flights on this route on a daily basis.
The traffic grew just 1.18 per cent in September, as per the latest available official data.
DGCA said its directive to IndiGo on complete change of all P&W engines with modified LPT by January 31 remains in force.
IndiGo Chief Executive Officer (CEO) Ronojoy Dutta and Qatar Airways CEO Akbar Al Baker signed the codeshare agreement in New Delhi.
IndiGo on Thursday signed a one-way codeshare agreement with Qatar Airways, allowing it to book seats on the former's flights.
Qatar has in the past shown interest in investing in IndiGo but the Indian airline has resisted.
IndiGo's outage comes as dozens of flights face delays or cancellations on Monday, according to reports
The regulator also asked IndiGo that all 97 such aircraft in its fleet must have modified PW engines by January 31 next year.
The announcement came after IndiGo's expansion of international flight operations this year.
The scrip of India's largest private airline, IndiGo, climbed 5.36 per cent to Rs 1,485.95 on the BSE.