Expression of regret for change.

表示对这一变化的遗憾。

youdao

Such letters should accordingly open with an apology, or at least an expression of regret, when an apology is really unnecessary.

回信的时候应当先对所提出的异议表示道歉，确实不需要道歉时，起码也得表示遗憾。

youdao

It can be an expression of regret for your personal actions.

这可以用来表示你后悔自己所做的事情。

I'm sorry 课堂 - SpeakingMax英语口语达人

Mr Kenny has offered an expression of regret for the stigma attached to former inmates.

BBC: Magdalene laundries: UK women's 'fast settlement' calls

"It was a very sincere and heartfelt expression of regret over any stress that they've suffered over the course of the last few years as a result of the media attention, " she added.

BBC: US cyclist Lance Armstrong apologises to Livestrong staff