"I don't know where I'll be next season. West Ham told me 'Bye bye' so I won't be with West Ham," the 33-year-old told the East London club's website.
"Now my focus is on the international team and the World Cup and then I'll think about next season," said Franco who was also a member of Mexico's 2006 World Cup squad in Germany.
Franco scored against England in Monday's 3-1 friendly defeat at Wembley Stadium moments after spraining his toe and underwent a scan straight after the match.
But he should be fit to spearhead Mexico's attack at the World Cup, which they kick off in the opening match of the tournament against hosts South Africa on June 11.
"I think for Mexico it (Monday's game) was a very important game because the same 11 players will probably start in South Africa as they did against England," Franco said.
He will be sidelined later on Wednesday for the warm-up against Netherlands in Freiburg, Germany, but hopes to be fit when Javier Aguirre's side play Italy in Brussels on June 3.
The Argentine-born player joined West Ham on a one-year deal after being released by Spanish side Villarreal but will now be leaving the club at the end of June.
Franco, who has also played for Club Atletico San Lorenzo de Almagro and CF Monterrey, scored five goals in 23 games for West Ham who finished just one place above the relegation zone.
‘He instantly popped into our ratings as one of the best U21 midfielders in Europe. The impressive thing is Slot has made him into more of a no.6' Inside Ryan Gravenberch's transformation at Liverpool
‘I don’t think Liverpool would look at Ollie Watkins, a striker isn’t a pressing issue for them – it’s Arsenal who need one’ Former Reds star explains why his old club don’t need an out-and-out forward this summer
