Selecting elements from Data Frame which meet an if condition in R

I'm working with a data frame inside a function,and I have a problem in the syntaxis. This is the frame I'm working with:

c
   id nobs
1   1  117
2   2 1041
3   3  243
4   4  474
5   5  402
6   6  228
7   7  442
8   8  192
9   9  275
10 10  148

And this is the code I'm using.

threshold=250
c
for (i in c[1]){ 
    if(threshold > any(c[i,2])){
        print(c[i,1])
    }
}

What I want is to get the first element of the data frame is the condition is met, but I get the result: [1] 1 2 3 4 5 6 7 8 9 10. It only has to be: 1 3 6 8 10

Any help would be appreciated. Thanks in advance.