Israel, which has reportedly breached the Gaza ceasefire agreement 47 times so far, carried out fresh airstrikes on Rafah on Sunday, sparking concerns over possible casualties.
Earlier in the day, an Israeli tank shell struck a bus in northern Gaza, killing 11 Palestinians.
Meanwhile, Hamas has firmly denied the U.S. allegations that it was plotting attacks on civilians, calling the claims baseless and politically motivated.
Hamas said it did not violate the ceasefire accord.