A much-loved bookstore in Sydney's CBD has issued an apology after discovering a dating coach was instructing clients to practise "pick-up techniques" on female customers as they browsed for books.

Key points: Kinokuniya said customers were subjected to "unsolicited and unwanted attention"

Kinokuniya said customers were subjected to "unsolicited and unwanted attention" The bookstore issued a warning to people caught using "pick-up artists" techniques

The bookstore issued a warning to people caught using "pick-up artists" techniques The store has not received a response from the dating coach about the incidents

Kinokuniya, which claims to be Australia's largest bookstore, said it was forced to take action against a dating coaching company after numerous complaints of in-store harassment.

After investigating the issue, Kinokuniya management found the company was using the bookshop as a place for clients to get "practical experience" and try out "pick-up" strategies.

Kinokuniya has chosen not to name the dating agency but says it has demanded they keep out of the bookstore, which sits atop the Galleries on George Street.

Managing director Kawai Yusuke told the ABC he was "dismayed" people were using a bookshop as a place to target women.

"There was an intent to these interactions and our customers were not finding them to be positive," he said.

"They may have been operating for a while."

Mr Yusuke said several customers had contacted the store after being approached and staff noticed "some interactions that seemed forced".

The bookstore issued a warning on their Facebook to any other companies who may consider using Kinokuniya for "practice runs".

"We say don't come in."

In-store security will now be on alert to catch those bothering female customers. ( Supplied: Kinokuniya Sydney )

A number of women have since realised the true motivation behind interactions in the bookstore over recent months.

"This happened to me and I just thought it was some random moment. I'm so glad it's been addressed and hope it gets nipped in the bud," Hilary Locke said on Facebook.

"It's sad others have had that experience while just browsing books."

Ms Locke told the ABC she and a friend both had similar experiences and felt uneasy after being approached in a "very full-on" manner.

"[The man] was obviously trying very hard," she said.

"It seems to me that this coaching service was using Kino as a place for men who might be socially awkward, but also have an interest in comic books or manga as a way to get them talking to people."

Ms Locke said it was disappointing many women had to tolerate such behaviour while just trying to browse books.

Kinokuniya in-store security will now target anyone giving "unsolicited and unwanted attention" to others and customers are being urged to notify staff if they are uncomfortable.

Management said they hoped the behaviour of pick-up artists would not discourage genuine interactions between booklovers.

"The bookstore should be a place for discussion," Kinokuniya said.

Mr Yusuke told the ABC he had not yet received a response from the dating company.