"Insolvency is not an issue for us. We have sufficient liquidity and a reliable partner, Etihad, which has pledged its support through to October 2018," a spokeswoman from the airline told AFP.
The Berlin-based airline booked losses amounting to €1.2 billion for the last two years, and depends on cash infusions from key shareholder Etihad for survival.
It recently applied to the German states of Berlin and North Rhine-Westphalia for a public guarantee.
But the Air Berlin spokeswoman said customers can keep booking Air Berlin flights "without worries".
"We are flying reliably again and have a grip on operational problems," she said.
Acknowledging that complaints have soared over recent months, the spokeswoman said "it could take a while before all the cases are dealt with".
"But Air Berlin will meet all the legitimate demands of its clients," she pledged.
Executives from Germany's second-largest airline presented a massive restructuring plan in late September that included renting 38 aircraft with crew to Lufthansa and slashing 1,200 jobs - or one in seven of its workforce.
Amid its restructuring, it has also been hit by a series of flight cancellations and severe delays, including over the recent Whitsun long weekend.