The lines are said by Titania, the Queen of the Faries. Oberon, the Fairy King and her estranged lover, has put the juice of a mystical love flower in her eyes. The elixer makes the people(or fairies, as in this case) with the substance in their eyes fall deeply in love with the first creature they see.
Oberon is playing a trick on Titania to get even for her shunning him. He makes her fall madly in love with Bottom, whom Puck has just transformed into a donkey.
These lines are spoken to Bottom by Titiania, the Queen of the Fairies. The lines are found in 3.1.125-135