The low-cost airline publicly criticised eDreams this week and called on Google to ban 'misleading' advertisements by the screenscraper website.
It put additional pressure on Google after the search giant agreed to ban ads for 'deceptive or harmful financial products' like payday loans and related products.
It said Google should extend the ban to 'misleading' screenscraper websites like eDreams.
But eDreams said Ryanair itself is misleading the public by making false claims about the way the OTA operates.
"Ryanair is misleading the public when it claims that we apply 'hidden fees' and that we sell 'inflated fares', which is not possible on any carrier," said a spokeswoman for eDreams.
She said the eDreams service charge is not hidden or added at the final booking stage. Instead customers can choose their payment card at the very first stage of the search process.
The full price breakdown, including service charges, is available in the top right hand corner of the screen, once customers have chosen their preferred flight, she added.
She also denied claims by Ryanair that eDreams tries to fool customers by imitating the airline's own website, using the Ryanair name and using identical branding.
"There is no intention to imitate the appearance of specific airlines as eDreams clearly displays all available flight options, with all airlines, to its customers making a search on one of its websites, no matter how they arrived at our site," said the spokeswoman.
And she disputed Ryanair's claims about a recent ruling by the Advertising Standards Authority.
"The ASA recently acknowledged that eDreams can use relevant search terms and that it can promote its services through the use of search engine optimisation. This is a common business practice across many sectors," she said.
"The whole point of the service we provide is to search millions of possible combinations in a matter of seconds to give consumers the ability to book flights there and back with different airlines, to get the best value and most convenient combinations. Close to half of our customers book a combination of flights which cannot be booked on any single airline website. A small minority of airlines aren't happy with this."