Only on PC/Laptop. Iphone nor Android can do negotiations, though I'm hoping a future update will allow this.
I get plenty of these as well, as do many others most likely, and it's a pain to deal with (I did have a good offer for my scout player mind. £3m over the market value and 7T). Only way to avoid it is by getting that player to the next star so that they stop (it won't stop all of them mind).