The City midfielder damaged his ankle ligaments in the EFL Cup penalty shootout victory over Leicester on Tuesday night.
The 17-year-old picked up his problem in an innocuous challenge at the King Power
Stadium but Kevin De Bruyne and Raheem Sterling were fortunate to escape injuries after dangerous tackles during Saturday's 4-1 win over Tottenham.
Harry Kane and Dele Alli were given yellow cards for a studs-up challenge on Sterling and an over-the-ball tackle on De Bruyne respectively.
Guardiola suggested that, while a
clampdown on diving is important, officials need to be strong on dangerous challenges.
"[Foden] is injured. It's not good," Guardiola told a news conference ahead of City's game against Bournemouth on Saturday. "The
next fixtures he will not be available.
"We were lucky with Raz [Sterling] and Kevin
De Bruyne in the last game against
Tottenham -- really lucky. We were unlucky
with Phil against Leicester.
"It's ligaments, he could be out for a time. I
accept the referees have to be careful about
the diving players, but be careful to protect
the players. The most important thing is to
protect the players -- that is the first target
for the referees.
"We were scared, we thought it was the
bone, but it's just the ligaments. It will be
one month or maybe more that he will be
injured."
Guardiola could have better news on the
injury front with defenders Vincent
Kompany and John Stones close to returning
to first-team action.
Kompany has played just one of City's last six
games after suffering from a calf strain
while Stones has been missing for more
than a month with a hamstring injury. David
Silva has also missed the last two games for
personal reasons.
"[Kompany] is much better," Guardiola said.
"He's much, much better. I think in the next
days he will be ready. I don't know whether
tomorrow -- I have to speak to him after the
training session, we will see. John Stones is
coming back soon as well."
Sterling, who scored a 97th-minute winner
when City beat Bournemouth earlier this
season, will also be available.
The forward scored twice against
Tottenham on Saturday, despite being
racially assaulted on the morning of the
game with a man subsequently jailed for the
incident.
"My wish is that it doesn't happen again,"
Guardiola said on the incident. "That's all it
is. The authorities took a decision, so well
done. So hopefully it won't happen again."