The Poland international, 23, only joined the Gunners from Spezia in January in a deal worth £214million.
He has played 16 times for Mikel Arteta's side, scoring one goal.
But although he has started two Premier League games so far this season, he remains a fringe player as Gabriel and William Saliba are the trusted centre-back partnership.
As a result, Calcio Mercato journalist Daniele Longo has claimed both AC Milan and Roma are interested in bringing him in on loan.
It is understood they have proposed January deals to Arsenal.
However, the Premier League side have made it clear he is not for sale.
Arteta's men are light in the centre of defence.
This is because of the long-term injury to new signing Jurrien Timber - who was ruled out in August with an ACL tear and is not expected back any time soon.
Ben White can fill in as a fourth-choice centre-half if two of Saliba, Gabriel and Kiwior are unavailable.
But after that there is no obvious candidate, following the departure of Rob Holding.
Arsenal sit third in the Premier League, one point adrift of table toppers Manchester City.
They sit top of their Champions League group with three wins from four games.