Ashley Williams and Neil Taylor of Wales, Jonjo Shelvey of England, Iceland's Gylfi Sigurdsson, Eder of Portugal and Poland's goalkeeper Lukasz Fabianski all played a role for their respective nations.
"It's important that the players put that to bed now and concentrate on their football here until Euro 2016," Monk told a news conference ahead of Monday's Premier League game at home to Stoke City.
"I have spoken to them and they are fully aware of that."
The Welsh club are without a win in four league games, slipping from fourth to 11th in the table and since Monk took charge have struggled in games immediately following international breaks, losing five and winning only one.
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"It's a key period for us now," Monk added.
"All the players have come back from the break fit and in good shape, and it will be great to have this period together ahead of Monday.
"Stoke had an initial slow start to the season but they have picked up in recent weeks. They signed a lot of quality players in the summer and they have a strong squad."
Managed by a patriotic Welshman in Mark Hughes, Stoke were bottom but one earlier in the season, but have won their last three games in all competitions and are now only one point behind Swansea.
(Reporting by Steve Tongue; editing by Martyn Herman)
