It looks a little like one of the chickweeds.
Depending on the grass post emergent weed killers can work.
However, if you have more weeds than grass it is probably better to start over. Use a non-specific herbicide, dig the remains out, water, let the weeds sprout, kill them again and repeat until weeds don't sprout (at least 3 times) before amending the soil and replanting the grass
You could just keep mowing low and before the weeds go to seed and gradually pull the weeds out by hand. This is a tedious job and takes dedication. You will have to commit to a bucket of weeds a day for as long as it takes and you will probably have to go over the same area more than once.
Happy gardening in Hawaii. Gardens are where people grow.