New York Mayor Edward I. Koch rejected a call by state health officials to extend the crackdown on “high risk” sexual activity to include hotel raids by investigators as part of efforts to halt the spread of AIDS. “We will not send in sex police to hotels to ascertain the nature of sex practices between consenting adults,” Koch said by telephone from Tokyo, where he is vacationing. Koch contradicted state Health Commissioner David Axelrod, who said officials were prepared to crack down on “high risk” sexual practices in hotels as well as bathhouses and gay clubs. Gov. Mario M. Cuomo supported Axelrod’s statement, saying if a hotel promoted “high risk” sexual activity, it would be vulnerable to the regulations.