Martinelli has been called up for the upcoming Olympic qualifying tournament.
The event takes place from January 18 to February 9, which means that Martinelli would be unavailable for several league games.
But Arteta is unsure if the player will go, as Arsenal may be able to convince Brazil not to call up the teenager.
The Spaniard told the club website: "Well, in the middle of the season it's never ideal for players to go to that type of tournament.
"We'll discuss with the club whether there's an obligation, whether that's something that the player really wants to go to and we'll make a decision on that."