Garrett Yrigoyen spoke up Thursday evening after coming under fire when it was discovered he liked Instagram posts mocking transgender people, Parkland shooting survivors and immigrants ... then deleting his account.

Garrett owned up to it -- via a new Instagram account -- saying ... "I am sorry to those who I offended, and I also take full responsibility for my ‘likes’ on Instagram that were hurtful and offensive."

He also explains why he started a new account, adding ... "I decided to take it down and start fresh because I have learned an extremely valuable lesson and am taking steps to grow, become more educated, and be a better version of myself. I am not perfect, and I will never be anywhere close, but now I will always be more informed and aware of what I am liking and supporting, not just on Instagram, but in life.”