Amrabat was on Wednesday named in Morocco's African Cup of Nations squad, but was withdrawn on Thursday evening due to the groin injury he sustained while playing for his club against Tottenham last weekend.
"It's Official - Omar El Kaddouri replaces injured Nordin Amrabat," read a statement on the national team's official Twitter account.
Separate reports have estimated the Netherlands-born attacking midfielder will be out for three to four weeks.
Morocco are coached by Frenchman Herve Renard, who previously won the Nations Cup with both Zambia and the Ivory Coast.
The Atlas Lions are in Group C alongside defending champions Ivory Coast, Togo and the DR Congo.