head off

phrasal verb
1
to get in front of somebody in order to make them turn back or change direction
جلو کسی را گرفتن, مسدود کردن مسیر, سد راه شدن
synonym intercept
2
to take action in order to prevent something from happening
جلوگیری کردن, مانع شدن, پیشگیری کردن
He headed off efforts to replace him as leader.