Van Persie played for Netherlands in their 3-2 win over England at Wembley Stadium on Wednesday while Vermaelen featured in Belgium's 1-1 draw with Greece, but Wenger said they went into their games carrying injuries and have deteriorated since.
"We have a problem with Vermaelen that we have to assess today," a clearly irritated Wenger told reporters on Friday at Arsenal's training ground at London Colney, north of London.
"Van Persie has a little groin problem that we have to assess," he added, saying he was unhappy they were called up for Wednesday's friendlies.
"It's difficult to understand that our players had to go injured - it's disrespectful to the players."
Van Persie, who has scored 29 times for Arsenal this season, only played for the first half against England although Dutch coach Bert van Marwijk said after the game that no agreement had been reached with Arsenal to use him only for 45 minutes.
Vermaelen played 90 minutes for Belgium against Greece.
Wenger continued: "We played Tottenham on Sunday then they played an international, then we are at Liverpool on Saturday lunchtime, then face AC Milan next Tuesday. Any football player knows it's impossible to play four games at the top level like that.
"Personally I think international friendlies are becoming more difficult to accept."
While Wenger has doubts about Van Persie and Vermaelen and confirmed that Aaron Ramsey is still injured, he said Abou Diaby - who has only made two substitute appearances this season and not played since November - is set to return.
Tomas Rosicky is likely to also be fit.
Both Arsenal and Liverpool are approaching Sunday's game in good spirits following Arsenal's 5-2 comeback win over Spurs last Sunday and Liverpool's penalty shootout win over Cardiff City in the League Cup final at Wembley on the same afternoon.
Arsenal go into the match in fourth place while Liverpool are seventh with both in the hunt for a Champions League place next season.
