tug at somebody's heartstrings

tear/tug/pull at/on (one's)/the heartstrings

To elicit strong feelings of sympathy or fondness. I don't know why, but that piece of music always tears at my heartstrings. That documentary really pulls on the heartstrings—you'll want to adopt all of those kids after watching it.
See also: heartstring, on, pull, tear, tug

tug at somebody’s ˈheartstrings

make somebody feel strong emotions of sadness and pity: Advertisers often use babies and children to tug at your heartstrings.
See also: heartstring, tug