Ribery to miss Bundesliga restart
"It's disappointing he hasn't been able to train with the team," Van Gaal told the club's website during a mid-season break in Dubai.
"This week was very important for our teamwork but now we'll have to reintroduce him during a competitive period. That's hard for him, for me, and for the other players."
Van Gaal said Ribery trained in socks on Friday but could not join in practice.
He will not face Hoffenheim next Friday when the Bundesliga resumes after the winter break.
Ribery has not played for three months after also suffering knee ligament damage. The problem with his toes flared up during the team's last practice before leaving Munich for the Middle East.