The midfielder concedes that he needs to play a series of full matches for Arsenal before the final round of World Cup qualifiers in October
Roy Hodgson's side, who sit at the top of Group H, one point clear of Ukraine, face Montenegro and Poland at Wembley on October 11 and 15 in the final round of qualification fixtures.
However, Wilshere says he will only be able to take part if he manages to play a series of full games for Arsenal.
"I'd probably say I'm 85-90 per cent fit, I've not played many 90 minutes," the 21-year-old is quoted as saying by Sunday Mirror.
"I came off for Arsenal against Tottenham because I was ill and I got two 60 minutes under my belt for England.
"It takes time to get to 100 per cent again. It takes five or six 90 minutes, then you start feeling strong.
"I feel good, but I've got that bit extra to go."