Well for one, Islam didn't exist back when Jesus was walking on the earth, so Jesus didn't say anything specific about Islam at all. Islam came into existence through Muhammad... he is the founder of it.
Being unrighteous to people is never good. And persecuting people as infidels, when they themselves are infidels is just hypocrisy. Even those who are not infidels, but faithful to God's words are not authorized by God to go around and be wicked. The ways of evil do not represent Him. The gospel of Jesus is the way to life and salvation.... it is the message to save people out of bondage and the path of destruction. You can't come to God through religion, but only through your heart, because that's what God is seeking. He is the Righteous Spirit, the Spirit of Truth, Goodness, Love, and Life.
He is Righteousness and His Truth combined. Truth without love and righteousness, or any part which is omitted gives an inaccurate picture of who God is. God will gather His outcasts and the remnant of His people, but these are those who cling to His words and have received His Spirit, the Spirit which is made available to us by trusting in Jesus and calling upon His name, asking Him for forgiveness of sins, knowing that the sacrifice that Jesus made on the cross to pay for our sins is the only way we can be reconciled to God.