Meaning of constrain

(verb) compel to behave in a certain way; "Social relations impose courtesy"; "duty constrains one to act often contrary to one's desires or inclinations"

to close within bounds, or otherwise limit or deprive of free movement; "This holds the local until the express passengers change trains"; "About a dozen animals were held inside the stockade"; "The illegal immigrants were held at a detention center"; "The terrorists held the journalists for ransom"

severely restrict in scope or extent; "tighten the rules"; "stiffen the regulations"