It should be noted that true dreams are not only for the Muslims; rather a non-Muslim may also see a true dream that may come to pass as he saw it. One of the clearest examples of that, in our opinion, is the dream of the king whose story Allah has told us, in the story of Yoosuf (Joseph - peace be upon him), when he saw seven fat cows being eaten by seven lean cows, and he saw seven green ears of corn and seven others that were dry. The Prophet Yoosuf (Joseph - peace be upon him) interpreted the dream for him. The two prisoners who were with him also saw dreams and he interpreted them for them.
Because of the dream of the King - who was not Muslim -the people of Egypt were saved from the famine that befell them after that dream. We ask Allah to make your dream a cause of your salvation and the salvation of many from that which is worse than famine.
We referred your dream to one of those who specialise in dream interpretation, and he rejoiced at it and was very optimistic about its interpretation and meaning. He told us that it is to be interpreted as it appears to be and does not need a great deal of explanation; it gives you the glad tidings that you will enter Islam and will be a righteous Muslim who will call others to this religion, in sha Allah (if Allah wills).
In more detail: your entering Makkah (Mecca) - in your dream - signifies your entering Islam, because no one can enter Makkah except a Muslim, and the white garments are what are worn by the pilgrim who performs Umrah or Hajj (pilgrimage to Makkah). And the pure, white holy Book is the Holy Qur'an.
This is good news for you, in sha Allah; may Allah hasten its fulfilment for you and cause you to save yourself by announcing your testimony that Allah, may He be exalted, is One and that He has no partner or associate, and that Muhammad (blessings and peace of Allah be upon him) is His Messenger. This is the religion of Islam that Allah, may He be exalted, has chosen for His creation, and with which He sent His slave and Messenger Muhammad (blessings and peace of Allah be upon him), to convey it to the world. You can find out more about Islam by going to an Islamic Centre in your city, where you will find brothers who will help you to find out about that which is in your best interests in this world and in the Hereafter.
May Allah bless you and keep you, and open your heart to the straight path.
Reproduced from Islam QA