Why did Yosef aggravate his brothers further by relating his dreams to them, even though they were unable to communicate with him peacefully?
Seforno: Once again, he acted out of immaturity, based on his young age. 1
Rosh, Moshav Zekenim: He was a Chacham, and saw a clear prophecy. One who withholds (does not tell) his prophecy is Chayav Misah bi'Yedei Shamayim (Sanhedrin 89a). He said, it is better that I be in danger through people - maybe Hashem will save me [than to Vadai be liable to Shamayim].
Ohr ha'Chayim #1: He wanted to inform them that Shamayim elevated him, and Yaakov merely consented, and then they will cease to hate him.
Ohr ha'Chayim #2: He wanted to inform them that they will need him and come to bow to him, so they will distance their hatred lest he take vengeance on them when they fall into his hands. The Shevatim would accept Hashem's decree.
Ohr ha'Chayim #3: He wanted to draw their hearts close. Dreams follow the interpretation. One should tell dreams to one who loves him, so he will interpret them favorably. He told them to show that his heart is full or brotherly love for them! Since they already felt hatred and envy, they judged that he wants to rule over them.
Malbim: Yosef in his virtue and purity of soul thought that his brothers love him, and they will interpret his dreams favorably, for dreams follow the interpretation. The brothers could not bear his words of Shalom, and all the more so his words that showed that he considers them friends!
Why does it say that they hated him more for his dreams, before it says what they were?
Malbim: Before they even heard it, they considered him brazen (Ha'amek Davar - a vain flatterer), without shame to cover his hatred with loving words. They did not want to hear the dreams.
