Jordan's King Hussein has sent a message to Israel's Prime Minister Menachem Begin in which he reportedly indicates conditions may be ripe for peace with Israel and expresses an interest in the peace process. The message was delivered by two Americans - Hubert Humphrey Jr. and Mark Segal, formerly adviser on Jewish affairs under President Jimmy Carter - who spoke with King Hussein a week ago and then came to Israel.
Mr. Humphrey told Israel radio that he and the King discussed ''the relationship between this country (Israel) and Jordan'' as well as ''the question of whether the PLO would continue to be a legitimate representative of Palestinian interests'' in light of the recent internal strife within that organization.
He said that there was no commitment by the King to ''making changes at this point'' and that he believed the King's recognition of the PLO's changed circumstances ''provides a basis for further discussions'' to try to renew peace talks. After receiving this message, Begin extended a new invitation to Hussein to join the peace process.