Surah 45:14 tells Muslims to forgive unbelievers, while Surah 9:29 commands them to fight unbelievers.
As usual the said verses:
45:14
Tell those who believe, to forgive those who do not look forward to the Days of God: It is for Him to recompense (for good or ill) each People according to what they have earned.
9:29
Fight those who believe not in God nor the Last Day, nor hold that forbidden which hath been forbidden by God and His Apostle, nor acknowledge the religion of Truth, (even if they are) of the People of the Book, until they pay the Jizya with willing submission, and feel themselves subdued.
The second verse is from surah named at Taubah (repentance). The surah is also called Bara’ah (released) meaning sort of termination of contract. At the beginning, the surah refers to a peace treaty between the muslims government in medina with the non muslims. Of course there are many things that has to be adhered to by the unbelievers (and they agreed) as well as the muslims. In the surah it was told that most of the non muslims have breached the agreement made between the two parties. As it was told in:
9:10
In a Believer they respect not the ties either of kinship or of covenant! It is they who have transgressed all bounds
Therefore, the Muslims government was required to fight those people who have violated the agreement except if they pay the Jizya (sort of like a tax for unbelievers as their contribution besides the zakat by the muslims – refer 9:29). I have to mention here that not all the unbelievers are affected. It was told in the same surah:
9:4
(But the treaties are) not dissolved with those Pagans with whom ye have entered into alliance and who have not subsequently failed you in aught, nor aided any one against you. So fulfil your engagements with them to the end of their term: for God loveth the righteous.
And
9:6
If one amongst the Pagans ask thee for asylum, grant it to him, so that he may hear the word of God; and then escort him to where he can be secure. That is because they are men without knowledge.
They have adequate… in fact… legal reason to fight the unbelievers.
So, no contradiction.