Arsène Wenger has told Lukas Podolski and Thomas Vermaelen that he is not willing to sanction transfers for them, as he placed the emphasis on maintaining Arsenal's squad stability in the summer and adding quality rather than quantity.

The manager is preoccupied with finishing the season with a flourish and his team could ensure a top-four place and a 17th consecutive Champions League qualification with a home win over West Bromwich Albion on Sunday . They might not need that if Everton were to lose or draw at home to Manchester City on Saturday.

There is also excitement at Arsenal about the FA Cup final against Hull City on 17 May, when the club could win their first trophy since 2005.

Wenger has admitted that the preparations for the transfer window have begun but he fears that the World Cup will represent an obstacle to early business.

Arsenal left it late last summer when they completed their major signing – Mesut Özil from Real Madrid for £42.5m – on deadline day and there is sure to be a clamour from their fans to make similar high-level purchases; ideally, in time for them to enjoy a pre-season.

Wenger stands to lose Bacary Sagna, Lukasz Fabianski and Nicklas Bendtner as free agents, though he is keen to keep the first two, and both Podolski and Vermaelen are expected to consider their options after seasons in which they have not been first-choices. But Wenger said that contracted players like them would not leave without his permission, and they did not have that.

"You might think it but these players are not necessarily open to a move," Wenger said. "We have only two players who are out of contract – Fabianski and Sagna [plus Bendtner]. All the rest need to have our agreement and they haven't got it yet."

Podolski sees himself as a striker whereas Wenger prefers him to play off the left, which has caused friction, partly because the player does not always embrace the defensive side of the game. He missed four months at the start of the season because of a hamstring tear but he has found his rhythm over recent weeks and Wenger highlighted his "efficient" numbers – 12 goals from 24 appearances, 17 of which have been as a starter.

"I was not convinced [by Podolski as a centre-forward]," Wenger said. "He can play as a second striker hanging behind but he's not a guy who likes contact up front. He likes to run in behind and get the ball to feet.

"He is a fantastic finisher, the one you want to have the ball in the box and that's why everyone says: 'Yes, he is a striker.' But when he plays completely up front, you don't feel he enjoys it. He likes to come to the ball and always come deep.

"He does not agree and, certainly, he thinks he is a striker. But he is a striker with somebody else who is a striker and has different qualities to him. He has over 100 caps for Germany and not one cap is in the middle. They are on the left. So you cannot say it is not his job."

Wenger said he had "people around me who start to look" for new signings and he predicted a "busy" summer. "But the main thing for us will be to keep the stability because we feel we are close," Wenger added. "We want to add something that makes us even stronger but number-wise, it will not be massive. Two or three? Yes.

"From my experience, the World Cup years have always been very quiet until the end of the World Cup, with no players reachable.

"I believe this year again you will have to wait until 15 July to start going."