David Moyes is looking to bring in another striker before the window slams shut, with West Ham having decided to sell Sebastien Haller to Ajax earlier this month.
He has zeroed in on En-Nesyri as an option and West Ham have put in a bid worth €30m for the Sevilla star.
It has been rejected by the Spanish club and, according to Madrid-based daily Marca, Sevilla want at least €40m before agreeing to let En-Nesyri move on.
The €40m would also not be able to be made up with add-ons, with Sevilla wanting the sum in an outright transfer fee and any bonuses to be on top of that.
It is unclear if West Ham are willing to go up to €40m to sign the Moroccan this month.
Sevilla only signed En-Nesyri 12 months ago, paying €20m to land him from Leganes, and want to double their money.
En-Nesyri has found the back of the net eight times in La Liga so far this season and four times in the Champions League.