Afrikaans - Ek het jou liefe
Albanian - te dashuroj
Alentejano(Portugal) - Gosto De Ti, Porra!
Alsacien - Ich hoan dich gear
Amharic - Afekrishalehou
Arabic - Ana Behibak (to a male)
Assamese - Moi tomak bhal pau
Basc - Nere Maitea
Batak - Holong rohangku di ho
Bavarian - I mog di narrisch gern
Bengali - Ami tomAy bhAlobAshi
Bengali - Ami tomake bhalobashi.
Berber - Lakh tirikh
Bicol - Namumutan ta ka
Bolivian - Quechua qanta munani
Bulgarian - Obicham te
Burmese - chit pa de
Cambodian - Bon sro lanh oon
Chinese/Cantonese - Moi oiy neya
Cantonese - Ngo oi ney
Corsican - Ti tengu cara (to female)
Corsican - Ti tengu caru (to male)
Croatian - LJUBim te
Czech - miluji te
Danish - Jeg elsker dig
Dutch - Ik hou van jou
Dutch - Ik ben verliefd op je
Ecuador - Quechua canda munani
English - I love you
English - I adore you
Esperanto - Mi amas vin
Estonian - Mina armastan sind
Estonian - Ma armastan sind
Farsi - Tora dust midaram
Farsi - Asheghetam
Farsi (Persian) - 0 doostat dAram
Filipino - Mahal ka ta
Filipino - Iniibig Kita
Finnish - Mina" rakastan sinua
French - Je t'aime
French - Je t'adore
Friesian - Ik hald fan dei
Gaelic - Ta gra agam ort
German - Ich liebe Dich
Greek - s'ayapo (spoken s'agapo, 3rd letter is lowercase’ gamma')
Greek (old) - (Ego) philo su (ego is only needed for mphasis)
Greenlandic - Asavakit
Gujrati - Hoon tane pyar karoochhoon.
Hausa - Ina sonki
Hawaiian - Aloha I'a Au Oe
Hebrew - Ani ohev otach (male to female)
Hebrew - Ani ohev otcha (male to male)
Hebrew - Ani ohevet otach (female to female)
Hebrew - Ani ohevet otcha (female to male)
Hindi - Mai tumase pyar karata hun (male to female)
Hindi - Mai tumase pyar karati hun (female to male)
Hokkien - Wa ai lu
Hopi - Nu' umi unangwa'ta
Hungarian - Szeretlek
Hungarian - Szeretlek te'ged
Icelandic - Eg elska thig
Indi - Mai Tujhe Pyaar Kartha Ho

Indonesian - Saya cinta padamu (Saya, commonly used)
Iranian - Mahn doostaht doh-rahm
Italian - ti amo (if it's a relationship/lover/spouse)
Italian - ti voglio bene (if it's a friend, or relative)
Japanese - Kimi o ai shiteru
Japanese - Aishiteru
Japanese - Chuu shiteyo
Japanese - Ora omee no koto ga suki da
Japanese - Ore wa omae ga suki da
Japanese - Suitonnen
Japanese - Sukiyanen
Japanese - Watashi Wa Anata Ga Suki Desu
Japanese - Watashi Wa Anata Wo Aishithe Imasu

Japanese - Suki desu (used at 1st time, like for a start, when you are not yet real lovers)
Javanese - Kulo tresno
Kannada - Naanu Ninnanu Preethisuthene
Kannada - Naanu Ninnanu Mohisuthene
Kiswahili - Nakupenda
Klingon - qabang
Konkani - Aau tuzo mog karta
Korean - No-rul sarang hae (man to woman in casual relation)
Korean - Tangsinul sarang ha yo
Korean - Tangshin-ul sarang hae-yo
Korean - Tangsinul Sarang Ha Yo
Korean - Tangshin-i cho-a-yo (i like you, in a romantic way)

Korean - Nanun tangshinul sarang hamnida
Korean - Nanun Dangsineul Mucheog Joahapnida
Korean - Nanun Dangsineul Saranghapnida
Korean - Nanun Gdaega Joa
Korean - Nanun Gdaereul Saranghapnida
Korean - Nanun Neoreul Saranghanda
Korean - Gdaereul Hjanghan Naemaeum Alji
Korean - Joahaeyo
Korean - Saranghae
Korean - Saranghaeyo
Korean - Saranghapanida
Kurdish - Ez te hezdikhem
Lao - Koi muk jao
Lao - Khoi huk chau
Latin - Te amo

Source: www.wikipedia.com